ˈsea-apple [apple n.] †1. The sea-urchin. Obs. 1666[see sea-egg 1].1752J. Hill Hist.Anim. 199 The roundish Centronia, with crooked..spines, the Sea apple. 2. The sea-coconut (see coco 6). 1864Grisebach Flora W. Ind. Islands 787 Sea-apple: Manicaria Plukenetii.