A synonym is a word (or a phrase) which means the same thing as another word or phrase.

Examples:

• car and automobile
• baby and infant
• child and kid
• make and create.
• student and pupil
• sick and ill
• scared and frightened
• rich and wealthy

Synonyms can be nouns, verbs, adverbs or adjectives, but both words must be of the same part of speech. That means, only a noun can be a synonym of another noun, only a verb can be a synonym of another verb, and so on.

One can find sets of synonyms in a thesaurus, which is a book listing groups of related words.