bashful
abashed, blushing, confused, constrained, coy, diffident, easily embarrassed, nervous, overmodest, reserved, reticent, retiring, self-conscious, self-effacing, shamefaced, sheepish, shrinking, shy, timid, timorous
Antonyms
aggressive, arrogant, bold, brash, conceited, confident, egoistic, fearless, forward, immodest, impudent, intrepid, pushy (informal) self-assured