Définir belong to the 2
nd group. Définir is a common french verb.
Définir is conjugated the same way that verbs that end in :
-ir
Définir is conjugated with
auxiliary avoir.
Définir verb is
direct transitive.
French verb définir can be conjugated in the reflexive form:
Se définir
Définir verb is a direct transitive verb, so passive voice can be used.