What figure of speech is defined as a comparison between two unlike things using "like," "as," or "than"?

The definition provided specifically describes a simile, which is a figure of speech that makes a comparison between two unlike things using the words "like," "as," or "than." This technique is often employed to create vivid imagery or to elucidate a concept by comparing it to something familiar. For instance, saying "her smile was like sunshine" compares the brightness of her smile to the warmth and illumination of the sun, allowing for a clearer understanding of the emotion being conveyed.

In contrast, a metaphor directly states that one thing is another, without using "like" or "as," thereby asserting a stronger equivalence. Hyperbole involves exaggeration for emphasis or effect, while a paradox presents a seemingly contradictory statement that may reveal an underlying truth. Each of these other figures of speech serves different purposes in language and literature, but only a simile fits the specific criteria laid out in the question.