an inward stroke; esp in an engine, the stroke that moves the piston away from the crankshaft
instroke in American English
(ˈinˌstrouk)
noun
1.
a stroke in an inward direction
2. (in an engine)
the stroke during which the piston moves into the cylinder
Word origin
[1885–90; in + stroke1]This word is first recorded in the period 1885–90. Other words that entered Englishat around the same time include: foregut, reactor, roller coaster, sensitization, toner