lime 1 |līm| noun (also quicklime) a white caustic alkaline substance consisting of calcium oxide, obtained by heating limestone. • (also slaked lime) a white alkaline substance consisting of calcium hydroxide, made by adding water to quicklime. • (in general use) any of a number of calcium compounds, esp. calcium hydroxide, used as an additive to soil or water. • archaic birdlime. verb [ trans. ] 1 treat (soil or water) with lime to reduce acidity and improve fertility or oxygen levels. • [often as adj. ] ( limed) give (wood) a bleached appearance by treating it with lime : limed oak dining furniture. 2 archaic catch (a bird) with birdlime. DERIVATIVES limy |ˈlīmē| adjective ( limier , limiest ). ORIGIN Old English līm, of Germanic origin; related to Dutch lijm, German Leim, also to loam . lime 2 noun 1 a rounded citrus fruit similar to a lemon but greener, smaller, and with a distinctive acid flavor. 2 (also lime tree) the evergreen citrus tree that produces this fruit, widely cultivated in warm climates. • Citrus aurantifolia, family Rutaceae. 3 a bright light green color like that of a lime : [as adj. ] day-glo orange, pink, or lime green. ORIGIN mid 17th cent.: from French, from modern Provençal limo, Spanish lima, from Arabic līma; compare with lemon . lime 3 (also lime tree) noun another term for linden , esp. the European linden. ORIGIN early 17th cent.: alteration of obsolete line, from Old English lind (see linden ).