Main Entry:

re·act

Pronunciation:

\rē-ˈakt\

Function:

verb

Etymology:

New Latin reactus, past participle of reagere, from Latin re- + agere to act — more at agent

Date:

1644

intransitive verb 1 : to exert a reciprocal or counteracting force or influence —often used with on or upon 2 : to change in response to a stimulus 3 : to act in opposition to a force or influence —usually used with against 4 : to move or tend in a reverse direction 5 : to undergo chemical reaction transitive verb : to cause to react