A verb can be identified through morphological, syntactical and semantic
parameters.
Morphological parameters
- a verb is a unit which has the features of mood and tense
combined with the morphological features person, number and, for
the participle, gender.
Semantic parameters are not easily delimited, due to the
heterogeneous nature:
- the verb expresses a process and an action made by the subject (but
also suffered).
The above definitions can be drawn on the basis of the classic grammar.
In the framework of the formal grammar
the verb is defined on the basis of its valency,
i.e. the capability of governing a given number of arguments having
specific syntactic and semantic roles.
Syntactic parameters:
- the verb is the head of a syntactic constituent, i.e. a verbal
phrase.
Semantic parameters:
- the verb governs arguments having syntactic and semantic roles: subject - agent; object - patient, etc.
- verbs can be subdivided into main (all the lexical verbs) and auxiliar (essere, avere and sometimes, in Italian, also venire). See 3.4 for further details.