Words may be related in form (as discussed in Chapter Four). They may also be related in sense. This kind of lexical relation is dealt with in some dictionaries. But many dictionaries list words as separate entries, failing to reveal the semantic network of the lexicon. One task of lexical semantics is the study of lexical sense relations.

　6.4.1 Synonymy
　6.4.2 Antonymy
　6.4.3 Homonymy
　6.4.4 Polysemy
　6.4.5 Hyponymy