Exertion, 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; as, an exertion of strength or power; an exertion of the limbs or of the mind; it is an exertion for him to move, to-day.
Syn. -- Attempt; endeavor; effort; essay; trial. See Attempt.
Shades of meaning
Fernald has no entry of its own for exertion; he lists it under act, endeavor, exercise, industry, work.
Where he writes about it:
Act is used, also, for the simple exertion of power; as, an act of will. — from act
Effort denotes the voluntary putting forth of power to attain or accomplish some specific thing; it reaches toward a definite end; exertion is a putting forth of power without special reference to an object. — from endeavor
Every effort is an exertion, but not every exertion is an effort. — from endeavor
A struggle is a violent effort or strenuous exertion. — from endeavor
Exercise, in the ordinary sense, is the easy natural action of any power; exertion is the putting of any power to strain and tax. — from exercise
But by qualifying adjectives we may bring exercise up to the full sense of exertion; as, violent exercise. — from exercise
Synonyms
actendeavorexerciseindustryworkaccomplishmentachievementactionactivityapplicationassiduityattemptattentionbusinessconstancyconsummationdeeddiligencedoingdrilldrudgeryeffecteffortemploymentessayexecutionexploitfeatintentnesslabormotionmovementoccupationoperationpainspatienceperformanceperseverancepersistencepractiseproceedingproductproductionsedulousnessstruggletoiltransactiontrialuse