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).
Derivatives:
spleenful adj. spleeny adj.
Etymology: ME f. OF esplen f. L splen f. Gk splen
Useful english dictionary. 2012.