Weight gainer is a common term used in the fitness world to describe a supplement that aids in weight gain and muscle building. However, there are several synonyms that can be used in the place of weight gainer, such as mass gainer, muscle builder, and weight enhancer. These synonyms are used interchangeably with weight gainer, but they convey a slightly different meaning. Mass gainer, for instance, refers to a supplement that promotes overall muscle mass gain, while weight enhancer emphasizes the ability to add extra pounds to a user's weight. Ultimately, the choice of synonym depends on the specific type of supplement and the goals of the user.