1. the word class that serves as the predicate of a sentence;
2. a content word that denotes an action, occurrence, or state of existence;
The Collaborative International Dictionary of English v.0.48:
Verb \Verb\, n. [F. verbe, L. verbum a word, verb. See Word.]
1. A word; a vocable. [Obs.] --South.
2. (Gram.) A word which affirms or predicates something of
some person or thing; a part of speech expressing being,
action, or the suffering of action.
Note: A verb is a word whereby the chief action of the mind
[the assertion or the denial of a proposition] finds
Active verb, Auxiliary verb, Neuter verb, etc. See
Active, Auxiliary, Neuter, etc.
WordNet (r) 3.0 (2006):
n 1: the word class that serves as the predicate of a sentence
2: a content word that denotes an action, occurrence, or state