Lexicon

The lexicon contains ``definitions'' of words in a machine-usable form. A lexicon entry may contain:

• The root word spelling

• Parts of speech (noun, verb, etc.)

• Semantic markers, e.g., animate, human, concrete, countable.

• Case frames that describe how the word is related to other parts of the sentence (especially for verbs).

• Related words or phrases. For example, United States of America should usually be treated as a single term rather than a noun phrase.

Modern language processing systems put a great deal of information in the lexicon; the lexicon entry for a single word may be several pages of information.