The Lexeme Concept

The lexeme concept

If we ask how many words are listed in (1) we can give at least two answers

(1) {cat, cats}

In one sense there are obviously two, but in another sense there is only one word, cat, and only one entry will be found in a dictionary for it. The plural, cats, is formed by a completely general rule from the singular form cat and there is no need to record the plural form separately. In addition, we can describe cat as “the singular form of the word cat” and cats as “the plural form of the word cat.” This gives us another interpretation for the term “word,” as becomes clear when we look at the word “sheep.” Here the singular form of the word sheep has exactly the same shape as the plural form, even though these are distinct linguistic entities. Given the vagaries of English orthography, this identity of shape can be true of the spoken form, the written form, or both (as with “sheep”). Thus, the written shape of the base form of the verb “read” (pronounced like “reed”) is identical to that of the past tense, “read” (pronounced like “red”) despite the difference in pronunciation, while the taxes, the tax’s (“of the tax”) and the taxes’ (“of the taxes”) differ solely in spelling.

It is rather useful to have different terms for these three different senses of the word “word.” We will therefore say that there is a lexeme cat which has two word forms, cat and cats. The names of lexemes are conventionally written in small capitals. The grammatical description “the singular / plural of cat” is a grammatical word. Thus, sheep is one word form corresponding to one lexeme, but it is two grammatical words (the singular and the plural of sheep).

We can think of a lexeme as a complex representation linking a (single) meaning with a set of word forms, or more accurately, linking a meaning with a set of grammatical words, which are then associated with corresponding word forms. From the point of view of the dictionary (or lexicon), this is therefore a lexical entry. There is no demand here that the set of forms correspond to only one meaning, or that only one set of forms correspond to a given meaning. If several forms correspond to one meaning we have pure synonymy: e.g. {boat, boats}, {ship, ships}. If a single form corresponds to more than one completely unrelated meaning, as with {write, right, rite}, or {bank, bank} then we have homophony or homonymy. We then treat the homophones /homonyms as distinct lexemes which just happen to share the same shape (written and / or spoken). In some cases these meanings are felt as related to each other, and we have a case of polysemy. Thus, the word “head” means a body part, the person in charge of an organization, a technical term in linguistics, and so on, and these meanings are associated by some kind of metaphorical extension. In general, polysemy tends to be either ignored (where the meanings are close) or treated like homophony. 

In linguistics a form-meaning pair is a sign and the lexeme is a prototypical example of a sign. The traditional definition of morpheme is “the smallest meaningful component of a word,” and this entails that we consider all morphemes as signs. However, this turns out to be very controversial, for some types of morpheme, at least.