apiscor, apisceris, apisci C, aptus sum (Dep.) Verb
Conjugation: Consonant Conjugation (3)
This is a deponent verb. It gave up ("deponere") its active forms (even though they still exist). Such verbs occur in passive voice but are translated in active voice.
For example: "loquor" (Form analysis: 1. Person Sg. Present Passive, "to say") translates to: "I say", NOT "I am said" because it is a deponent verb.