diffident

adjectives

showing modest reserve

"she was diffident when offering a comment on the professor's lecture"

diffident

is derived from

is similar to

marked by self-restraint and reticence

"was habitually reserved in speech, withholding her opinion"-Victoria Sackville-West

lacking self-confidence

"stood in the doorway diffident and abashed"; "problems that call for bold not timid responses"; "a very unsure young man"

diffident, shy, timid, unsure

is derived from

antonym