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