1540s, "pertaining to the spleen," from Late Latin spleneticus, from splen (see spleen). Meaning "irritably morose" is from 1590s. Alternative splenic (1610s) is from French splénique (16c.).
Gloomy, Sullen, Sulky, Morose, Splenetic. These words are arranged in the order of their intensity and of their degree of activity toward others. [Century Dictionary]
