As defined by dictionary.com:
1. artfully or affectedly shy or reserved; slyly hesitant; coquettish.
2. shy; modest.
3. showing reluctance, esp. when insincere or affected, to reveal one's plans or opinions, make a commitment, or take a stand: The mayor was coy about his future political aspirations.
4. Archaic. disdainful; aloof.
5. Obsolete. quiet; reserved.
Man, I wish you could have seen the poses I got yesterday when I asked for "coy".