scleroid adjective 2noun 2forms 3 adjective2 •Having a hard texture.The shells of nuts are scleroid. •thickened.Did you find his drums were thickened and scleroid ? — 1953 noun2 •A plant cell with thick cell walls.At the end of gall formation isolated scleroids are differentiated in the gall parenchyma, and much more rarely, tracheids and vessels. — 1961 •The outermost layer of an eyeball.This is caused by the scleroid which turns around the optic nerve, and projects somewhat above it, thus forming, when illuminated, the clear scleroidal margin. — 1860 formsscleroids · more scleroid · most scleroid