A white caustic alkaline substance consisting of calcium oxide, obtained by heating limestone. A rounded citrus fruit similar to a lemon but greener, smaller, and with a distinctive acid flavor. The evergreen citrus tree that produces the lime, widely cultivated in warm climates. A bright light green color like that of a lime. Treat (soil or water) with lime to reduce acidity and improve fertility or oxygen levels. Catch (a bird) with birdlime.