Open class words belong to a list of morphemes which can be added to by absorbing new words, such as technical terms, slang, as well as adoptions and adaptations of foreign words.
The list of groups of words that belong to the open class type include:
- noun
- main verb, (however not auxiliary verbs)
- adjective
- adverb
- interjection
Closed-class words such as prepositions, conjunctions, pronouns, etc., are words belonging to a class to which no new words can be added readily.