Leery
Part of speech: adjective
Definition: Cautious, hesitant, or nervous about something; having reservations or concerns.
Wary
Part of speech: adjective
Definition: Cautious of danger; carefully watching and guarding against deception, artifices, and dangers; timorously or suspiciously prudent; circumspect; scrupulous; careful.Characterized by caution; guarded; careful.
Example sentence: I don't like spontaneity; there you go. I'm wary of it.