Related prehistorically to Old English verb hydan "to hide" (see hide (v.1)), the common notion being of "covering." The alliterative pairing of hide and hair (often negative, hide nor hair) was in Middle English (early 15c.), but earlier and more common was hide ne hewe, literally "skin and complexion ('hue')" (c. 1200).
a measure of land (obsolete), Old English hid "hide of land," earlier higid, from hiw- "family," from or related to hiwan "household," hiwo "a husband, master of a household," from Proto-Germanic *hiwido-, from PIE *keiwo- (source also of Latin civis "citizen"), from PIE root *kei-(1) "to lie," also forming words for "bed, couch," and with a secondary sense of "beloved, dear."
The notion was of "amount of land needed to feed one free family and dependents," usually 100 or 120 acres, but the amount could be as little as 60, depending on the quality of the land. Often also defined as "as much land as could be tilled by one plow in a year." Translated in Latin as familia.