n. [ Back, a. + side. ] The hinder part, posteriors, or rump of a person or animal. [ 1913 Webster ]
☞ Backside (one word) was formerly used of the rear part or side of any thing or place, but in such senses is now two words. [ 1913 Webster ]
n. [ Back, adv. + sight. ] (Surv.) The reading of the leveling staff in its unchanged position when the leveling instrument has been taken to a new position; a sight directed backwards to a station previously occupied. Cf. Foresight, n., 3. [ 1913 Webster ]