Synonyms for Know-it-all:

adj.

boastful (adjective)
loudmouth.

n.

prig, wise guy, individualist, wisenheimer, smart aleck, tin god, smarty, Malapert, wiseacre, Saucebox, upstart, smarty-pants, Witling, wisecracker, prima donna, good, snob, extrovert, God's gift. braggart (noun)
gasbag, egoist, narcissist, loudmouth, braggart, swaggerer, swellhead, blusterer, windbag, boaster, blower, bluffer.
know-it-all (noun)
know-all.
one who claims full knowledge (noun)
braggart, windbag, smart aleck, wiseacre, smarty-pants, wise guy.
smart aleck (noun)
swellhead, smarty, smarty-pants.

Other synonyms:

Saucebox, wisecracker, Witling, smarty-pants, wiseacre, smarty, wisenheimer, wise guy. smart aleck. Other relevant words:
individualist, upstart, know-all, extrovert, Malapert, good, wisecracker, smarty-pants, Saucebox, smart aleck, Witling, prig, wiseacre, smarty, wisenheimer, snob, wise guy.