Entry 3 senses · 2 variants Webster, 1913 Coralline · Cor·al·line · IPA a. n. 01 a. Composed of corallines; as, coralline limestone. 1. Composed of corallines; as, coralline limestone. 02 n. A submarine, semicalcareous or calcareous plant, consisting of many jointed branches. 1. A submarine, semicalcareous or calcareous plant, consisting of many jointed branches.(Bot.) 2. Formerly any slender coral-like animal; -- sometimes applied more particulary to bryozoan corals.(Zool.)