c. 1300, "proud, valiant, strong," from Old French estout "brave, fierce, proud," earlier estolt "strong," from a Germanic source from West Germanic *stult- "proud, stately, strutting" (source also of Middle Low German stolt "stately, proud," German stolz "proud, haughty, arrogant, stately"), from PIE root *stel- "to put, stand, put in order," with derivatives referring to a standing object or place.
Meaning "strong in body, powerfully built" is attested from late 14c., but has been displaced by the (often euphemistic) meaning "thick-bodied, fat and large, bulky in figure," which is first recorded 1804. Original sense preserved in figurative phrase stout-hearted (1550s). Related: Stoutly; stoutness.
"short and stout," 1820, probably a varied reduplication of roll (v.). As a noun, it was used as the name of various bowling ball games from 1713, and it was used as early as 1610s in the sense of "rascal." As an appellation of a short, stout person, by 1836.
"fleshy, portly, stout," late 14c., from Old French corpulent "stout, fat," from Latin corpulentus "fleshy, fat," from corpus "body" (from PIE root *kwrep- "body, form, appearance") + -ulentus "full of." Leigh Hunt was sent to prison for two years for calling the Prince Regent corpulent in print in 1812.