One that exercises: an exerciser of racehorses. (noun)
A device for exercising the body.(noun)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "exerciser" in a sentence
"The transferable feature is no problem since the exerciser is the one who has to pass muster."
"Lorin Maurer was a health-conscious eater and a dedicated exerciser, which is not surprising since the 30-year-old was an All-American swimmer who was once captain of the Wilson High School girls swim team."
"If I were to glance out the window I would see the occasional forlorn exerciser stolidly jogging off to nowhere and back, or a dog walker slogging ankle-bone-deep through the beige quicksand-like sand: early risers, God bless 'em."