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 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.

Definitions

see: Lemma (linguistics) Depending on the language, words can be difficult to identify or decipher. Dictionaries take upon themselves the task of categorizing a language's lexicon into lemmas. These can be taken as an indication of what constitutes a "word" in the opinion of the authors.

Word boundaries

In spoken language, the distinction of individual words is usually given by rhythm or accent, but short words are often run together. See clitic for phonologically dependent words. Spoken French has some of the features of a polysynthetic language: il y est allé ("He went there") is . Since the majority of the world's languages are not written, the scientific determination of word boundaries becomes important.

There are five ways to determine where the word boundaries of spoken language should be placed:

Potential pause

A speaker is told to repeat a given sentence slowly, allowing for pauses. The speaker will tend to insert pauses at the word boundaries. However, this method is not foolproof: the speaker could easily break up polysyllabic words.

A speaker is told to say a sentence out loud, and then is told to say the sentence again with extra words added to it. Thus, I have lived in this village for ten years might become I and my family have lived in this little village for about ten or so years. These extra words will tend to be added in the word boundaries of the original sentence. However, some languages have infixes, which are put inside a word. Similarly, some have separable affixes; in the German sentence "Ich komme gut zu Hause an," the verb ankommen is separated.

This concept was proposed by Leonard Bloomfield in 1926. Words are thought of as the smallest meaningful unit of speech that can stand by themselves. This correlates phonemes (units of sound) to lexemes (units of meaning). However, some written words are not minimal free forms, as they make no sense by themselves (for example, the and of).

Some languages have particular rules of pronunciation that make it easy to spot where a word boundary should be. For example, in a language that regularly stresses the last syllable of a word, a word boundary is likely to fall after each stressed syllable. Another example can be seen in a language that has vowel harmony (like Turkish): the vowels within a given word share the same quality, so a word boundary is likely to occur whenever the vowel quality changes. Nevertheless, not all languages have such convenient phonetic rules, and even those that do present the occasional exceptions.