Which word describes something that is rounded in figure or plump?

The term that best describes something that is rounded in figure or plump is "rotund." This word is often used to refer to a shape that is full, rounded, or even spherical, particularly when describing a person or object that appears plump or portly. Its connotation is generally neutral or even positive, evoking a sense of fullness that can be associated with vitality or health.

Other options in the question do not relate to the description of a rounded or plump figure. "Salacious" refers to something that is sexually provocative or lustful, often with negative connotations. "Sardonic" describes a form of humor or wit that is grimly mocking or cynical. "Shunt" is a term primarily used in a mechanical or medical context, referring to the act of moving something from one place to another, often in a way that involves redirection or avoidance. None of these terms encapsulate the notion of roundness or plumpness inherent in "rotund."