Final answer:
Enlargement due to an increase in cell size is known as hypertrophy, seen in examples like muscle growth from exercise.
Step-by-step explanation:
Enlargement of a structure due to an increase in the size of its cells is called hypertrophy. This term is specifically used in biology to describe the growth of tissue through an increase in the size of its cells rather than the number of cells. One of the most common examples of hypertrophy is seen in muscle tissue, where, for instance, regular exercise can lead to an increase in the size of skeletal muscle cells. Enlargement due to an increase in cell size is known as hypertrophy, seen in examples like muscle growth from exercise.