Thesaurus.com
Dictionary.com
Definitions

flippant

[flip-uhnt] / ˈflɪp ənt /
ADJECTIVE
irreverent
Synonyms
STRONGEST
cheeky cocky disrespectful glib offhand playful rude
WEAK
brassy breezy flighty flip fresh frivolous impertinent impudent insolent lippy nervy pert sassy smart smart-alecky superficial
Antonyms
STRONGEST
mannerly nice respectful
WEAK
courteous reverent serious

From Roget's 21st Century Thesaurus, Third Edition Copyright © 2013 by the Philip Lief Group.