Noun

(en noun)

The work involved in performing an activity; exertion.

* , chapter=23

, title= The Mirror and the Lamp , passage=The slightest effort made the patient cough. He would stand leaning on a stick and holding a hand to his side, and when the paroxysm had passed it left him shaking.}}

* {{quote-news, year=2011, date=June 22, author=Press Association, work=The Guardian

, title= Manchester United offer Park Ji-sung a new two-year contract , passage=The 30-year-old South Korean, who joined United in 2005, retired from international duty after last season's Asian Cup in an effort to prolong his club}}

* {{quote-magazine, year=2013, month=July-August, author=(Henry Petroski)

, title= Geothermal Energy , volume=101, issue=4, magazine=(American Scientist) , passage=Energy has seldom been found where we need it when we want it. Ancient nomads, wishing to ward off the evening chill and enjoy a meal around a campfire, had to collect wood and then spend time and effort coaxing the heat of friction out from between sticks to kindle a flame.}}

An endeavour.

* {{quote-magazine, date=2012-03, author=William E. Carter, Merri Sue Carter

, volume=100, issue=2, page=87, magazine=(American Scientist) , title= The British Longitude Act Reconsidered , passage=But was it responsible governance to pass the Longitude Act without other efforts to protect British seamen? Or might it have been subterfuge—a disingenuous attempt to shift attention away from the realities of their life at sea.}}

A force acting on a body in the direction of its motion.

(Rankine)