Meaning of mechanical equivalent of heat

mechan'ical equiv'alent of heat'

Pronunciation: [key]
  1. (in any system of physical units) the number of units of work or energy equal to one unit of heat, as 4.1858 joules, which equals one small calorie.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.