In my teenage period (1950s) making out was 'going
all the way.' Sometime since, making out has come to mean petting (groping,
touching, fondling). The word petting seems to be vanishing in
the 21st Century.
Before grandfather and grandmother married, they had
sexual intercourse (fucked) in their teens but that sounded so harsh, so they called it making out.
Today, making out is just
fooling around, groping, and touching, but not having
intercourse.