rɪˈækt v. 1 intr. (foll. by to)
respond to a
stimulus;
undergo a
change or
show behaviour due to
some influence (how
did they react to
the news?). 2 intr. (often foll. by against) be actuated by
repulsion to; tend in a
reverse or
contrary direction. 3 intr. (often foll. by upon)
produce a
reciprocal or
responsive effect;
act upon the
agent (they react upon
each other). 4 intr. (foll. by with) Chem. &
Physics (of a
substance or particle) be the
cause of
activity or
interaction with another (nitrous
oxide reacts with the metal). 5 tr. (foll. by with) Chem. cause (a substance) to react with another. 6 intr.
Mil.
make a
counter-attack. 7 intr.
Stock Exch. (of shares)
fall after rising. [RE+ ACT or med.L reagere react(as
RE-, L agere do, act)]