We think of words as the basic units of language. When a baby begins to
speak, the way the excited mother reports what has happened is: ‘Sally
(or Tommy) has said her (or his) first word!’ We would be surprised at
a mother who described little Tommy’s or Sally’s first utterance as a
sentence. Sentences come later, we are inclined to feel, when words are
strung together meaningfully. That is not to say that a sentence must
always consist of more than one word. One-word commands such as
‘Go!’ or ‘Sit!’, although they crop up relatively seldom in everyday conversation
or reading, are not in any way odd or un-English. Nevertheless,
learning to talk in early childhood seems to be a matter of putting words
together, not of taking sentences apart.
There is a clear sense, then, in which words seem to be the buildingblocks
of language. Even as adults, there are quite a few circumstances
in which we use single words outside the context of any actual or reconstructable
sentence. Here are some examples:
• warning shouts, such as ‘Fire!’
• conventional commands, such as ‘Lights!’, Camera!’, ‘Action!’
• items on shopping lists, such as ‘carrots’, ‘cheese’, ‘eggs’.
It is clear also that words on their own, outside sentences, can be sorted
and classified in various ways. A comprehensive classification of English
words according to meaning is a thesaurus, such as Roget’s Thesaurus. But
the kind of conventional classification that we are likely to refer to most
often is a dictionary, in which words are listed according to their spelling
in alphabetical order