Synonyms are different words with almost identical or similar meanings. Words that are synonyms are said to be synonymous, and the state of being a synonym is called synonymy. The word comes from Ancient Greek syn (σύν) ("with") and onoma (ὄνομα) ("name"). The words car and automobile are synonyms. Similarly, if we talk about a long time or an extended time, long and extended become synonyms. In the figurative sense, two words are often said to be synonymous if they have the same connotation:

Synonyms can be any part of speech (such as nouns, verbs, adjectives, adverbs or prepositions), as long as both members of the pair are the same part of speech. Here are more examples of English synonyms:

Note that synonyms are defined with respect to certain senses of words; for instance, pupil as the "aperture in the iris of the eye" is not synonymous with student. Similarly, he expired means the same as he died, yet my passport has expired cannot be replaced by my passport has died.

In English, many synonyms evolved from the parallel use, in the early medieval period, of Norman French (from Latin) and Old English (Anglo-Saxon) words, often with some words being used principally by the Saxon peasantry ("folk", "freedom", "bowman") and their synonyms by the Norman nobility ("people", "liberty", "archer").