The word "chubbiest" refers to someone or something that is especially plump or round in shape. Some synonyms for this word include "fattest," "heaviest," "most overweight," "plus-sized," "rounder," and "chunkiest." These words all carry similar connotations and can be used interchangeably to describe a person or object that has a notably round or curvaceous appearance. While some may view these terms as less than complimentary, they can also be used in a more affectionate or jokey manner. Regardless of how they are used, these synonyms all convey the idea of abundant softness and plumpness.