c. 1200, "collection of things bound together," from Old French trousse, torse "parcel, package, bundle," of uncertain origin, perhaps from Vulgar Latin *torciare "to twist," from Late Latin torquere "to twist" (from PIE root *terkw- "to twist"). Meaning "surgical appliance to support a rupture, etc." first attested 1540s. Sense of "framework for supporting a roof or bridge" is first recorded 1650s.
c. 1200, "to load, load up," from Anglo-French trusser, Old French trusser, torser "to load, fill, pack, fasten" (11c.), from Old French trousse, torse (see truss (n.)). Related: Trussed; trussing.