countervail

 
Pronunciation: /ˌkaʊntəˈveɪl/

verb

[with object] (usually as adjective countervailing)
  • offset the effect of (something) by countering it with something of equal force: the dominance of the party was mediated by a number of countervailing factors

Origin:

late Middle English (in the sense 'be equivalent to in value'): from Anglo-Norman French contrevaloir, from Latin contra valere 'be of worth against'