It's rare that I read a book whose author regularly uses words I'm unfamiliar with. Thus, I present my list of new words from Avatars of the Word. (Bonus game for you: see how many you know without looking them up!)

rebarbativeness, page 3.
lability, page 10.
etiolated, page 94.
cynosure, page 101.
bumptious, page 116. This word (quite rightly) makes me think of the Bumpuses and their hounds in A Christmas Story.
suasion, page 169.
velleity, page 188.

Does anyone else think it's lame that the OED Online isn't free anymore?