A word is a basic element of language that carries an objective or practical meaning, can be used on its own, and is uninterruptible.[1] Despite the fact that language speakers often have an intuitive grasp of what a word is, there is no consensus among linguists on its definition and numerous attempts to find specific criteria of the concept remain controversial.[2] Different standards have been proposed, depending on the theoretical background and descriptive context; these do not converge on a single definition.[3]: 13:618 Some specific definitions of the term "word" are employed to convey its different meanings at different levels of description, for example based on phonological, grammatical or orthographic basis. Others suggest that the concept is simply a convention used in everyday situations.[4]: 6
The concept of "word" is distinguished from that of a morpheme, which is the smallest unit of language that has a meaning, even if it cannot stand on its own.[1] Words are made out of at least one morpheme. Morphemes can also be joined to create other words in a process of morphological derivation.[2]: 768 In English and many other languages, the morphemes that make up a word generally include at least one root (such as "rock", "god", "type", "writ", "can", "not") and possibly some affixes ("-s", "un-", "-ly", "-ness"). Words with more than one root ("[type][writ]er","[cow][boy]s", "[tele][graph]ically") are called compound words. In turn, words are combined to form other elements of language, such as phrases ("a red rock", "put up with"), clauses ("I threw a rock"), and sentences ("I threw a rock, but missed").
In many languages, the notion of what constitutes a "word" may be learned as part of learning the writing system.[5] This is the case for the English language, and for most languages that are written with alphabets derived from the ancient Latin or Greek alphabets. In English orthography, the letter sequences "rock", "god", "write", "with", "the", and "not" are considered to be single-morpheme words, whereas "rocks", "ungodliness", "typewriter", and "cannot" are words composed of two or more morphemes ("rock"+"s", "un"+"god"+"li"+"ness","type"+"writ"+"er", and "can"+"not").
Since the beginning of the study of linguistics, numerous attempts at defining what a word is have been made, with many different criteria.[5] However, no satisfying definition has yet been found to apply to all languages and at all levels of linguistic analysis. It is, however, possible to find consistent definitions of "word" at different levels of description.[4]: 6 These include definitions on the phonetic and phonological level, that it is the smallest segment of sound that can be theoretically isolated by word accent and boundary markers; on the orthographic level as a segment indicated by blank spaces in writing or print; on the basis of morphology as the basic element of grammatical paradigms like inflection, different from word-forms; within semantics as the smallest and relatively independent carrier of meaning in a lexicon; and syntactically, as the smallest permutable and substitutable unit of a sentence.[2]: 1285
In some languages, these different types of words coincide and one can analyze, for example, a "phonological word" as essentially the same as "grammatical word". However, in other languages they may correspond to elements of different size.[4]: 1 Much of the difficulty stems from the eurocentric bias, as languages from outside of Europe may not follow the intuitions of European scholars. Some of the criteria developed for "word" can only be applicable to languages of broadly European synthetic structure.[4]: 1-3 Because of this unclear status, some linguists propose avoiding the term "word" altogether, instead focusing on better defined terms such as morphemes.[6]