Middle English teyntour, tentour, tenture, probably borrowed from Medieval Latin tentōrium "tent, tabernacle, canopy, frame for stretching skins or cloth," going back to Latin, "shelter made of skins or cloth, tent," from ten-, stem in nominal derivation of tendere "to extend outward, stretch" + -tōrium, suffix of places, from neuter of -tōrius, deverbal adjective suffix — more at tender entry 3