1836, "small, crisp biscuit in the form of a knot, salted on the outside," from German Prezel, also Brezel, from Middle High German brezel, prezel, from Old High German brezitella, brecedela, from Medieval Latin *brachitella, presumably a kind of biscuit baked in the shape of folded arms (source also of Italian bracciatella, Old Provençal brassadel), diminutive of Latin bracchiatus "with branches, with arms," from bracchium "an arm, a forearm," from Greek brakhion "an arm" (see brachio-).
The figurative sense of "a thing much twisted" is by 1945. Soft pretzels are attested by 1893 in the German regions of Pennsylvania, but did not become widely popular until mid-20c.