early 15c., from Old French antelop, from Medieval Latin antalopus, anthalopus (11c.), from Late Greek antholops (Eusebius of Antioch, c.336 C.E.), in reference to a fabulous animal haunting the banks of the Euphrates, very savage, hard to catch and having long saw-like horns capable of cutting down trees. In modern zoology, the name was applied c. 1600 to a living type of deer-like mammal of India. In the western U.S., the name is used in reference to the pronghorn.
Original sense and language unknown (it looks like Greek "flower-eye," as if from anthos + ops, but that may be Greek folk etymology). It figures in heraldry, and also was known in Medieval Latin as talopus and calopus.