A word is the smallest free form (an item that may be uttered in isolation with semantic or pragmatic content) in a language, in contrast to a morpheme, which is the smallest unit of meaning. A word may consist of only one morpheme (e.g. cat), but a single morpheme may not be able to exist as a free form (e.g. the English plural morpheme -s).
Typically, a word will consist of a root or stem, and zero or more affixes. Words can be combined to create other units of language, such as phrases, clauses, and/or sentences. A word consisting of two or more stems joined together form a compound. A word combined with an already existing word or part of a word form a portmanteau.