n. The most important annual horse-race of England, founded in 1780 by the twelfth Earl of Derby, and run at Epsom, Surrey, in the spring, generally on the Wednesday before Whitsuntide.n. [lowercase] A masons' two-handled float.n. [lowercase] A stiff felt hat with rounded crown and more or less narrow brim, worn by men, and sometimes also by women, for walking or riding.Same as Derbian.