réagir

/ʁe.a.ʒiʁ/
1.
verbInf2nd

to react (emotionally or physically)

to respond (to an event or stimulus)

Il a très mal réagi à la nouvelle.

He reacted very badly to the news.

2.
verbInf2nd

to take action or intervene in response to a problem or situation

Il faut réagir vite pour limiter les dégâts.

We need to act quickly to limit the damage.

3.
verbInf2nd

to comment on or give feedback about something (message, document, post)

Je t'ai envoyé le dossier, peux-tu réagir dessus ?

I sent you the file—can you give some feedback on it?