calisthenics (n.) Look up calisthenics at
also callisthenics, kind of light gymnastics, 1847, (the adjective calisthenic/callisthenic is from 1839), formed on model of French callisthenie, from Latinized combining form of Greek kallos "beauty" (see Callisto) + sthenos "strength, power, ability, might" (perhaps from PIE root *segh- "to have, hold," on the notion of "steadfastness, toughness") + -ics.

The proper Greek, if there was such a word in Greek, would have been *kallistheneia. Originally, gymnastic exercises suitable for girls and meant to develop the figure and promote graceful movement. OED describes the word as "chiefly a term of young ladies' boarding-schools." A place for doing it was a calisthenium (1853).