From WordNet (r) 3.0 (2006):
apt
adj 1: (usually followed by `to') naturally disposed toward; "he
is apt to ignore matters he considers unimportant"; "I am
not minded to answer any questions" [syn: apt(p),
disposed(p), given(p), minded(p), tending(p)]
2: at risk of or subject to experiencing something usually
unpleasant; "he is apt to lose"; "she is liable to forget"
[syn: apt(p), liable(p)]
3: mentally quick and resourceful; "an apt pupil"; "you are a
clever man...you reason well and your wit is bold"-Bram
Stoker [syn: apt, clever]
4: being of striking appropriateness and pertinence; "the
successful copywriter is a master of apposite and evocative
verbal images"; "an apt reply" [syn: apposite, apt,
pertinent]