Definition of "rotund"

He was a plump little man and we had been walking uphill at a pace—set by him—far too rapid for his short legs. He breathed stertorously, and half the drops which glimmered on his rotund face were not rain but sweat.

1956, Delano Ames, chapter 23, in Crime out of Mind‎

Convex preferences may have indifference curves that exhibit “flat spots,” while strictly convex preferences have indifference curves that are strictly rotund.

1992, Hal R. Varian, Microeconomic Analysis (3rd ed.), W. W. Norton & Company, Inc., p. 96–97