"a joust, a combat," 1510s, perhaps from tilt (v.1) on the notion of "to lean" into an attack, but the word originally seems to have been the name of the barrier which separated the combatants, which suggests connection with tilt in an earlier meaning "covering of coarse cloth, an awning" (mid-15c.). This is perhaps from tilt (v.1), or related to or influenced by tent. Watkins derives it from Old English teld "awning, tent," related to beteldan "to cover," from Proto-Germanic *teldam "thing spread out." Hence, also full tilt (c. 1600). Pinball machine sense is from 1934.