1.
reaction; counteraction; recoil (physics)
In physics, the equal and opposite force described by Newton's Third Law. Describes phenomena such as the recoil of a gun or the thrust that propels a rocket.
作用と反作用の法則。
The law of action and reaction.
ロケットは反作用の原理で飛ぶ。
Rockets fly on the principle of reaction.
銃を撃つと反作用で体が押し戻される。
When you fire a gun, the recoil pushes your body back.
2.
backlash; adverse reaction; unintended consequence
Figurative use.
急な改革の反作用が出た。
There was a backlash from the rapid reforms.
薬の反作用に注意する。
To watch out for adverse reactions to medication.
規制を強めた反作用で、かえって違反が増えた。
As an unintended consequence of tightening regulations, violations actually increased.
In physics, refers to Newton's Third Law: for every action, there is an equal and opposite reaction. In general use, it describes negative consequences or pushback that result from an action.
COMMON COLLOCATIONS:
- 作用反作用: action and reaction
- 反作用の法則: law of reaction
- 反作用が生じる: a reaction occurs
SIMILAR WORDS:
- 副作用: side effect — specifically for medication or treatment side effects
- 反動: recoil, backlash — emphasizes the swing-back effect; also used politically
- 反発: repulsion, opposition — emphasizes emotional or social resistance