hare (n.)

Old English hara "hare," from Proto-West Germanic *hasan- (source also of Old Frisian hasa, Middle Dutch haese, Dutch haas, Old High German haso, German Hase), of uncertain origin; possibly the original sense was "gray" (compare Old English hasu, Old High German hasan "gray"), from PIE *khas- "gray" (source also of Latin canus "white, gray, gray-haired"). Perhaps cognate with Sanskrit sasah, Afghan soe, Welsh ceinach "hare." Rabbits burrow in the ground; hares do not.

þou hast a crokyd tunge heldyng wyth hownd and wyth hare. ["Jacob's Well," c. 1440]

"to harry, harass," 1520s; meaning "to frighten" is 1650s; of uncertain origin; connections have been suggested to harry (v.) and to hare (n.). Related: Hared; haring.