Английский Этимологический словарь - spare (v.)

- O.E. sparian "to refrain from harming, go free," from the source of O.E. spжr "sparing, frugal," from P.Gmc. *sparaz. The adj. meaning "additional, extra" is from c.1380. The noun meaning "extra thing or part" is from 1642. Spare rib is 1596, from meaning "absence of fat," or perhaps from M.L.G. ribbesper, from sper "spit," from P.Gmc. *speru, from PIE *sper- "pole, spear."