The origin of the word simile can be traced back to the Latin word similis, which meant “similar, resembling, like” and was first documented in English around the mid-14th century. Starting from the period of rhetoric to the present day a number of definitions of the term simile have been proposed. According to the most widely recognized dictionaries simile is “a comparison of one thing with another, usually in regard to a particular attribute, esp. as a figure of speech” (Oxford English Dictionary) and “an expression that describes something by comparing it with something else, using the words ‘as’ or ‘like’” (Longman Dictionary of Contemporary English). Some scholars state that simile “is fundamentally a figure of speech requiring overt reference to source and target entities, and an explicit construction connecting them" (Gibbs, 1994, p. 40) and "Like metaphor, it is a semantic figure, a mental process playing a central role in the way we think and talk about the world, which often associates different spheres" (Bredin, 1998, p. 68). In general, all above mentioned definitions imply that simile (a) involves comparison by pointing out a similarity or likeness between two things. It doesn’t just describe something in isolation. For example, saying "The runner was fast" is a description, whereas "The runner was as fast as a cheetah" is a comparison, and thus a simile. (b) The comparison is explicit and signaled by markers that can be grouped based on their grammatical category, such as verbs (seem, give appearance, look like, act like, sound like, resemble, remind of), adjectives (similar to, the same as), nouns (a sort of, some kind of), prepositions (like, as, as…as), and conjunctions (as if/though, as when).

Simile has been studied alongside metaphor across various fields like rhetoric, literary studies, linguistics, psychology, and cognitive science by scholars such as Aristotle, Mortara Garavelli, Wellek and Warren, Ortony, Bredin, Fromilague, Miller, Gibbs, and Glucksberg. Research has explored deeply its form and structure (e.g., Gargani, 2016; Cuenca, 2015), similarities and differences with metaphor (e.g., Haught, 2013; Bredin, 1998), and how similes are processed and understood (e.g., Veale, 2013; Ortony, 1985; Glucksberg & Keysar, 1990).

In linguistic theory, both simile and metaphor serve as fundamental tools for figurative expression, but their relationship remains a topic of ongoing scholarly debate. Structurally, similes resemble literal comparison statements (e.g., X is like Y), while metaphorical forms tend to omit comparative markers (e.g., X is Y). Despite their formal differences, these figures of speech often yield analogous interpretations. This similarity has led researchers to explore whether similes and metaphors are cognitively or conceptually connected (Israel et al., 2004).

One interpretative framework is the comparison theory, which traces back to classical rhetoric (Cicero, Quintilian) and is echoed in the work of Miller. According to this view, metaphors function as elliptical similes – statements that implicitly invoke comparison. For example, the metaphor Encyclopaedias are gold mines becomes interpretable when reformulated as the simile Encyclopaedias are like gold mines, where the literal comparison reveals the underlying semantic relation.

Aristotle provides an alternative, yet related, account. In Rhetoric (Aristotle, 3.4.2), he contends that similes are essentially metaphors, differing only in form. This line of reasoning has influenced contemporary theorists such as Ricoeur (Ricoeur, 2003, p. 293), who regards similes as attenuated metaphors, and Lakoff and Turner (Turner, 1989, p. 133), who assert that both similes and metaphors are rooted in conceptual metaphor. For instance, in both Encyclopaedias are gold mines and Encyclopaedias are like gold mines, the concept of a knowledge resource is structured by the metaphorical domain of wealth – implying that form does not significantly alter conceptual interpretation.

Conversely, Glucksberg (Glucksberg, 2001) proposes a class-inclusion model wherein metaphors and similes occupy distinct cognitive mechanisms. He posits that metaphors like John is a louse function by categorizing John under an abstract superordinate group – "contemptible beings" – with "louse" as its prototypical member. Here, the metaphor asserts category membership, while the corresponding simile John is like a louse merely invites comparison and requires metaphorical transformation to convey the same depth of meaning.

On the other hand, proponents of cognitive linguistics such as Croft and Cruse (Croft & Cruse, 2004, p. 212) argue for a clear distinction between metaphors and similes. They note that similes (A is like B) assert resemblance, while metaphors (A is B) predicate attributes directly, often evoking a more forceful or imaginative association. Relevance theorists like Carston (Carston, 2002) and O‘Donoghue (O‘Donoghue, 2009) also support this distinction, emphasizing differences in inferential processing.

Similes are investigated through multiple scholarly lenses – semantic, cognitive, and stylistic. Each perspective provides a distinct approach to understanding how similes function and why they are constructed the way they are. Fromilhague (Fromilhague, 1995, pp. 77–78) introduces a primary distinction between objective similes, rooted in sensory perception (seeing as), and subjective similes, emerging from individual conceptual associations (thinking as). This distinction reflects the cognitive origin of the comparison.

From a semantic standpoint, Grishkova N.V. identifies a broad range of source domains from which similes are drawn. She classifies them into several thematic fields. The animal group includes further subdivisions: wild animals (e.g., as big as an elephant, as blind as a bat), domestic animals (e.g., as strong as a bull, as meek as a lamb), and pets (e.g., as weak as a kitten, as agile as a cat). Other taxonomic fields comprise birds (e.g., as proud as a peacock, as graceful as a swan), fish (e.g., as dumb as a fish), insects(e.g., as busy as a bee, as angry as a wasp), religious and mythological references (e.g., as wise as Solomon, as old as Adam), natural phenomena (e.g., as clear as day, as cold as ice), colors (e.g., as white as snow, as black as coal), daily life expressions (e.g., to smoke like a chimney, as pretty as a picture), and food-related expressions (e.g., as cool as a cucumber, as hot as a pepper).

Another semantic categorization, suggested by Ortony (Ortony, 1993), separates literal and non-literal similes. Literal similes involve symmetric, interchangeable elements – e.g., Blackberries are like raspberries – where the reversal (Raspberries are like blackberries) remains coherent. In contrast, non-literal similes – e.g., Crime is like a disease – rely on asymmetrical mapping; reversing the comparison (A disease is like crime) either distorts the meaning or renders it nonsensical. Furthermore, non-literal similes can often be reformulated as metaphors (Crime is a disease), a transformation not applicable to literal cases (Blackberries are raspberries).

Bredin (Bredin, 1998, p. 77) contributes to this discussion by addressing the lifespan of similes, which can range from conventionalized expressions to creative comparisons. For example:

1. This meat is as tough as old boot leather exemplifies an idiomatic simile – a fixed, familiar comparison.
2. He is like a father to her represents a standard simile, common and semantically transparent.
3. Encyclopaedias are like gold mines qualifies as a fresh simile, introducing an original but interpretable connection.
4. She [Desdemona] was false as water demonstrates a creative simile, where the unexpected comparison to water suggests moral instability or emotional inconstancy.

Fromilhague (Fromilhague, 1995, pp. 83–84) also distinguishes between explicit and implicit similes. Explicit similes specify the shared feature of comparison – e.g., Music is like medicine because it takes away the pain (Roncero et al. 2006) – providing a rationale. Implicit similes, by contrast, rely on the interpretative abilities of the audience, as in He is like a father to her, where the nature of the resemblance must be inferred.

Some scholars categorize similes into two primary semantic groups based on their characteristics and usage. The first group consists of accurate similes that lack evaluative elements and are employed in neutral contexts. These similes serve as objective descriptors, presenting factual comparisons without subjective coloring. Their distinctive feature lies in their ability to convey information straightforwardly, unaffected by stylistic considerations or personal bias.

The second group comprises similes containing evaluative elements or stylistic markers. These comparisons go beyond mere description, incorporating the speaker’s perspective or emotional tone. Within this category, we find traditional similes that have become lexicalized through common usage, as well as individual, creative comparisons crafted by writers to produce original imagery. The latter often expand conventional comparisons or introduce completely novel analogies.

From a structural perspective, linguists identify two main types of similes. Converging similes typically employ the conjunction "as" or similar linking words, combined with short adjectives to establish comparisons. In contrast, contrasting similes utilize comparative forms of adjectives or adverbs, sometimes accompanied by negations, to highlight differences rather than similarities. While these distinctions are often framed as semantic categories, they primarily reflect grammatical construction patterns.

Additional semantic classifications further refine our understanding of similes. Objective similes draw from concrete, observable reality, while subjective similes emerge from personal associations and interpretations. The literal/non-literal distinction proves particularly significant, with non-literal similes connecting conceptually distant domains to create striking figurative comparisons.

In literary stylistics, explicit similes are defined as comparisons where the connection between two elements is overtly stated through linguistic markers such as “like” or “as.” These similes are easily identifiable due to their direct syntactic structure (Hayeesa-i & Maisarah, 2023, p. 216). For instance, in The Happiness of Kati, many of the similes follow this clear comparative pattern, contributing to their accessibility and frequency. Conversely, implicit similes (also known as covert or elliptical similes) involve more subtle comparisons where the relational marker may be omitted, or the similarity is implied through context rather than directly expressed. These require a deeper level of interpretation as the analogy is embedded within the surrounding discourse, demanding inferential understanding from the reader (ibid.).

XiuGuo (XiuGuo, 2005) delineates five principal categories of similes, each serving a distinct stylistic and semantic function.

A descriptive simile conveys a visual or physical representation of an entity by likening it to another object, thereby enhancing its perceptibility. For instance, in the sentence “Lisa made O with her lips, moving her mouth like a whale eating,” the simile highlights the configuration of Lisa’s lips by drawing a parallel with the mouth movement of a whale. This type foregrounds the physical resemblance between the compared entities, thereby enriching the descriptive imagery.

An illuminative simile functions to deepen the reader’s understanding of an object’s traits by articulating its features more vividly. Consider the example: “My heart still hurts, and the sizeable knot above my left temple looked, the colonel thought, like a miniaturized topographical map of Macedonia.” Here, the knot is not only described but contextualized through a complex visual analogy, offering insight into its intricate shape and prominence. This type reveals the inner essence or salient qualities of the compared object (ibid.).

The illustrative simile is used to portray an object’s behavior or condition by linking it to a more familiar or observable action. For example, “Mia followed the smoke rings with her fingers, stabbing at them like a kid trying to pop bubbles” illustrates the action’s playful and futile nature by likening it to a child’s gesture. The comparison illustrates not just what the subject does but how it is perceived experientially and visually (ibid.).

An open simile refers to a comparison that evokes a particular quality without explicitly detailing the attributes involved. It relies on the interpretive ability of the reader to deduce the implied characteristics. For instance, “We ran like we had golden shoes” does not state the specific traits of golden shoes but invokes notions of speed, lightness, or perhaps value and privilege. This ambiguity is central to the open simile’s stylistic function (ibid.).

A closed simile, on the other hand, explicitly outlines the traits shared by the subject and the comparative object. It does not merely hint at similarities but articulates them clearly. In the sentence “A cylindrical orange object is getting bigger and bigger, like a fast-approaching sun,” the comparison explicitly identifies the shape, color, and motion of the object in relation to the sun, thus offering a complete and detailed analogy (ibid.).

These categories are supported by Perrine’s (Perrine, 2012) broader conceptualization of simile as “the declaration of a relationship of similarity between two entities that are substantially different but are considered equal in one or more respects.” Building on Fromilhague’s tripartite model, a simile typically comprises three components: the Comparandum(the subject being described), the Comparatum (the element it is compared to), and the Shared Trait(s) (the qualities they have in common), which may be either implicit or explicitly expressed.

In sum, similes and metaphors, while differing in surface form, share deep conceptual and cognitive connections that have sparked extensive scholarly exploration. The comparison theory, classical rhetoric, and contemporary cognitive frameworks all highlight how these figures of speech function as interpretative tools, shaping how we conceptualize and communicate meaning. While some scholars, like Aristotle and Ricoeur, view similes as metaphors, others, such as Glucksberg and other theorists, argue for distinct cognitive and semantic processes. Beyond theoretical distinctions, similes display remarkable diversity in structure, function, and usage. From literal and objective comparisons to creative and implicit analogies, similes operate across stylistic, semantic, and cognitive dimensions. All mentioned classifications of simile underscore their role as tools for enhancing expressivity, clarity, and imagination in discourse. By examining these varied perspectives, it becomes evident that similes are essential devices for mapping understanding across disparate domains, reflecting both shared cognition and individual creativity.