reacter
nounUS /ɹiˈæktɚ/ · UK /ɹiːˈæktə/
Etymology From react + -er.
1
One who reacts.
- While he is easier to work with than the one who reacts quickly to whatever happens, the slow reacter rarely makes other than his routine contributions to what's going on.1972, Philip Roger Marvin, Man in motion: a winning game plan for executives, page 107: