(of a part of a machine) moving backwards and forwards in a straight line

the reciprocating piston of a traditional internal combustion engine

respond to (a gesture or action) by making a corresponding one

the favour was reciprocated

perhaps I was expected to reciprocate with some remark of my own

(of a part of a machine) move backwards and forwards in a straight line

when you're shooting most semi-automatic handguns, the slide reciprocates as part of the firing cycle