Lexical knowledge describes knowledge about words. The goal of the lexical knowledge is to describe all information about words and their relationships. The lexical knowledge includes several information aspects of linguistic theory such as morpho-syntactical, semantical, pragmatical and lexical aspect.

The morpho-syntactical aspect describes the words, their constitutive parts and specifies how words combine structurally. The semantic aspect describes the meaning of a word in terms of the concepts of some knowledge base. It specifies how words can be combined to express the several meaning. The pragmatic aspect describes information such as connotation, implicature, style, etc. The lexical aspect describes intern lexical constraints and relations between different linguistic units and compounds such as homonymy, synonymy, antonymy, hypernymy, hyponymy, etc.