noun

1. a usually colorless, crystalline mineral consisting of pure carbon, with nearly perfect cleavage and the greatest hardness of any substance: unflawed, transparent stones are cut into gems of great brilliance, and less perfect forms are used for cutting tools, abrasives, etc.
2. a gem or other piece cut from this mineral
3. 1. a lozenge-shaped plane figure (♦)
   2. any of a suit of playing cards marked with such figures in red
   3. this suit of cards
4. ☆ Baseball
   1. the infield
   2. the whole playing field

Etymology: ME diamaunt < OFr diamant < ML diamas (gen. diamantis), for L adamas < Gr, adamant, diamond

adjective

1. of, like, or set with a diamond or diamonds
2. marking or celebrating the 60th, or sometimes 75th, year a diamond jubilee

transitive verb