Thesaurus.com
Dictionary.com
Definitions

vanquish

[vang-kwish, van-] / ˈvæŋ kwɪʃ, ˈvæn- /
VERB
defeat soundly
Synonyms
STRONGEST
conquer crush overcome overpower quell repress rout subdue surmount
STRONG
beat humble overturn overwhelm reduce subjugate subvert trample
WEAK
bear down put down triumph over
Antonyms
STRONGEST
give in let go lose release surrender win yield
WEAK
fail

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