v.
Pronunciation: r ē - ' akt
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