Definitions of exercise:

• noun:   the activity of exerting your muscles in various ways to keep fit

  Example: "The doctor recommended regular exercise"

• noun:   a task performed or problem solved in order to develop skill or understanding
• noun:   systematic training by multiple repetitions
• noun:   (usually plural) a ceremony that involves processions and speeches

  Example: "Academic exercises"

• noun:   the act of using
• verb:   do physical exercise
• verb:   give a work-out to

  Example: "Some parents exercise their infants"

• verb:   learn by repetition
• verb:   put to use
• verb:   carry out or practice; as of jobs and professions