Definition of "carthorse"

carthorse

noun
plural carthorses
1. A large, strong horse used for pulling heavy loads.
  Quotations
  The blacksmith's forge shone bright on the opposite side of the way, and the proprietor had the hind-leg of a carthorse in his leather-coated lap.
  1840, Horace Smith, editor, Memoirs, Letters, and Comic Miscellanies in Prose and Verse, of the Late James Smith‎
  He is not a man of independent fortune, for he works like a carthorse.
  1852, Charles Dickens, Household Words
  Athelstan Arundel walked home […], foaming and raging. […] He walked the whole way, walking through crowds, and under the noses of dray-horses, carriage-horses, and cart-horses, without taking the least notice of them.
  1892, Walter Besant, “Prologue: Who is Edmund Gray?”, in The Ivory Gate […], New York, N.Y.: Harper & Brothers, […], page 16