This word is acceptable for play in the US & UK dictionaries that are being used in the following games:

• Lexulous
• Wordscraper
• Wordosaur

n. The act or an instance of exerting, especially a strenuous effort.

n. An expenditure of physical or mental effort.

n. The act of exerting, or putting into motion or action; the active exercise of any power or faculty; an effort, esp. a laborious or perceptible effort.

n. The act of exerting; the act of putting into motion or action; effort; a striving: as, an exertion of strength or power; an exertion of the limbs or of the mind.

n. Synonyms Endeavor, attempt, trial.

n. use of physical or mental energy; hard work

"Hence he has found it practically the greatest economy of mental labor to work vigorously when he is disposed to do so, and to refrain from exertion, so far as possible, _when it is felt to be an exertion_. ""

labor    toil    labour   

least resistance    overexertion    application    exercising    strain    pull    exercise    friction    difficulty    physical exercise   

attempt    endeavor    effort    essay    trial   

Cistercian    assertion    coercion    desertion    insertion    reassertion   

toil    effort    zeal    devotion    perseverance    hardship    anxiety    fatigue    labors    achievement