n. 1 an abdominal organ involved in maintaining the proper condition of blood in most vertebrates. 2 lowness of spirits; moroseness, ill temper, spite (from the earlier belief that the spleen was the seat of such feelings) (a fit of spleen; vented their spleen). spleenful adj. spleeny adj.
[ ME f. OF esplen f. L splen f. Gk splen ]