"application with the hands of pressure and strain upon muscles and joints of the body for therapeutic purposes," 1874, from French massage "friction of kneading" (by 1819), from masser "to massage," possibly from Arabic massa "to touch, feel, handle;" if so, probably the word was picked up in Egypt during the Napoleonic campaign there. Another possibility (suggested by the writings of 18c. French traveler Guillaume Joseph Le Gentil) is that French got it in colonial India from Portuguese amassar "knead," a verb from Latin massa "mass, dough" (see mass (n.1)). Massage parlor first attested 1894, from the start it was a euphemism or disguise name for "house of prostitution."
"apply massage to, treat by means of massage," 1874, from massage (n.). Figurative sense of "manipulate" (data, etc.) is by 1966. Related: Massaged; massaging.