WordReference Random House Learner's Dictionary of American English © 2025
coun•ter•act /ˌkaʊntərˈækt/USA pronunciation
v. [~ + object]
coun•ter•ac•tion /ˌkaʊntərˈækʃən/USA pronunciation n. [countable]
coun•ter•ac•tive, adj.
coun•ter•ac•tive•ly, adv.
WordReference Random House Unabridged Dictionary of American English © 2025- to act in opposition to; frustrate by contrary action:This medicine will counteract the effects of the disease.
coun•ter•ac•tion /ˌkaʊntərˈækʃən/USA pronunciation n. [countable]
coun•ter•ac•tive, adj.
coun•ter•ac•tive•ly, adv.
coun•ter•act
(koun′tər akt′),USA pronunciation v.t.
coun′ter•ac′tant, adj.
coun′ter•act′er, coun′ter•ac′tor, n.
coun′ter•act′ing•ly, adv.
coun′ter•ac′tion, n.
coun′ter•ac′tive, adj.
coun′ter•ac′tive•ly, adv.
- to act in opposition to;
frustrate by contrary action.
- counter- + act 1670–80
coun′ter•act′er, coun′ter•ac′tor, n.
coun′ter•act′ing•ly, adv.
coun′ter•ac′tion, n.
coun′ter•ac′tive, adj.
coun′ter•ac′tive•ly, adv.
- neutralize, counterbalance, contravene, thwart.
'counteraction' also found in these entries (note: many are not synonyms or translations):