Muscle-builder is a term used to describe individuals, supplements or programs that focus on building muscles. There are several synonyms for the word muscle-builder, including bodybuilder, weightlifter, strength trainer, athlete, muscle developer, and power-builder. Each of these terms describes someone who works to increase muscle mass and strength, either through physical activity, weight training, or specialized diets. While the term muscle-builder may be specific to those who engage in bodybuilding or competitive weightlifting, it is important to understand the broader range of terms that describe the physical work and effort required to build muscle mass and improve strength.