apt (Adjective) — (usually followed by 'to') naturally disposed toward. ex. "he is apt to ignore matters he considers unimportant"
apt (Adjective) — At risk of or subject to experiencing something usually unpleasant. ex. "he is apt to lose"
apt (Adjective) — Mentally quick and resourceful. ex. "an apt pupil"
apt (Adjective) — Being of striking appropriateness and pertinence. ex. "an apt reply"