Counteract /(koun`t?r-?kt")/

Coun·ter·act

Counteract

v. t.

imp. & p. p. Counteracted; p. pr. & vb. n. Counteracting

  1. To act in opposition to; to hinder, defeat, or frustrate, by contrary agency or influence; as, to counteract the effect of medicines; to counteract good advice.