Main entry: shy, timid, unsure, diffident
Definition: lacking self-confidence
Usage: stood in the doorway diffident and abashed; problems that call for bold not timid responses; a very unsure young man
Antonyms: confident
Definition: having or marked by confidence or assurance
Main entry: diffident
Definition: showing modest reserve
Usage: she was diffident when offering a comment on the professor's lecture
Antonyms: unreserved
Definition: not cautious or reticent
Antonyms: unreserved
Definition: not reserved