exercise

Etymology

From Middle English exercise, from Old French exercise, from Latin exercitium.

noun

1. (countable) Any activity designed to develop or hone a skill or ability.
   The teacher told us that the next exercise is to write an essay.
2. (countable, uncountable) Activity intended to improve physical, or sometimes mental, strength and fitness.
   Swimming is good exercise.
   I like to do my exercises every morning before breakfast.
   I do crosswords for mental exercise.
   Regular mental exercise keeps the circuits of the brain active and healthy and reduces the risk of dementia. 2018, Timothy R. Jennings, The Aging Brain, page 107
3. A setting in action or practicing; employment in the proper mode of activity; exertion; application; use.
   The law guarantees us the free exercise of our rights.
   December 8, 1801, Thomas Jefferson, first annual message exercise of the important function confided by the constitution to the legislature
4. The performance of an office, ceremony, or duty.
   I assisted the ailing vicar in the exercise of his parish duties.
5. (obsolete) That which gives practice; a trial; a test.

verb

1. To exert for the sake of training or improvement; to practice in order to develop.
   to exercise troops or horses;  to exercise one's brain with a puzzle
2. (intransitive) To perform physical activity for health or training.
   I exercise at the gym every day.
3. (transitive) To use (a right, an option, etc.); to put into practice.
   The tenant exercised his option to renew the tenancy.
   She is going to exercise her right to vote.
4. (now often in passive) To occupy the attention and effort of; to task; to tax, especially in a painful or vexatious manner; harass; to vex; to worry or make anxious.
   exercised with pain
5. (obsolete) To set in action; to cause to act, move, or make exertion; to give employment to.