Counteraction is the noun for that pushing-back: the action, or the effect, that reduces or prevents harm by working the opposite way. If a drug makes you sleepy, a cup of coffee might be called the counteraction — though a doctor would more often keep the verb and say the coffee counteracts it. The noun is bookish. Scientists, older writers, and formal reports use it. In ordinary talk people prefer the verb counteract, or they just name the second action. Though actually, students sometimes reach for counteraction when they mean reaction. A reaction is any answer. A counteraction is specifically an opposite-effect answer.