By external structure of the word we mean its morphological structure. For example, in the word post-impressionists the following morphemes can be distinguished: the prefixes post-, im-, the root press, the noun-forming suffixes -ion, -ist, and the grammatical suffix of plurality -s. All these morphemes constitute the external structure of the word post-impressionists.
The external structure of words, and also typical word-formation patterns, are studied in the section on word-building (see Ch. 5, 6).
The internal structure of the word, or its meaning, is nowadays commonly referred to as the word's semantic structure. This is certainly the word's main aspect. Words can serve the purposes of human communication solely due to their meanings, and it is most unfortunate when this fact is ignored by some contemporary scholars who, in their obsession with the fetish of structure tend to condemn as irrelevant anything that eludes mathematical analysis. And this is exactly what meaning, with its subtle variations and shifts, is apt to do.
The area of lexicology specialising in the semantic studies of the word is called semantics (see Ch. 7, 8).
Another structural aspect of the word is its unity. The word possesses both external (or formal) unity and semantic unity. Formal unity of the word is sometimes inaccurately interpreted as indivisibility. The example of post-impressionists has already shown that the word is not, strictly speaking, indivisible. Yet, its component morphemes are permanently linked together in opposition to word-groups, both free and with fixed contexts, whose components possess a certain structural freedom, e. g. bright light, to take for granted (see Ch. 12).
The formal unity of the word can best be illustrated by comparing a word and a word-group comprising