Unified Medical Language System® (UMLS®)
There is one lexical entry for each spelling or set of spelling variants in a particular part of speech. Each lexical record contains information on:
- Base form of the term
- The part of speech
- A unique identifier
- Rules for spelling variants
The base form of a term is the uninflected form of the item; the singular form in the case of a noun, the infinitive form in the case of a verb, and the positive form in the case of an adjective or adverb.
The lexicon recognizes eleven parts of speech:
Approximately eighty-six percent of the entries are nouns.