What is another word for an increase in muscle size?

Another word for an increase in muscle size is hypertrophy.

Muscle hypertrophy occurs when individual muscle fibers become larger, increasing the overall size of a muscle. In resistance training, repeated tension, fatigue, and recovery stimulate adaptations that can enlarge the fibers over time. The process is different from hyperplasia, which would mean an increase in the number of muscle fibers.

Training is only one part of the picture. Adequate protein, total calories, sleep, and recovery all influence how effectively the body can build and repair muscle tissue. Progressive overload—gradually increasing resistance, repetitions, or training demand—is commonly used to provide an ongoing growth stimulus.

Hypertrophy is often confused with a temporary workout “pump,” which is caused largely by increased blood flow and fluid shifts. A pump can make muscles look larger for a short time, but lasting hypertrophy develops through repeated training and recovery over weeks and months.