From The Collaborative International Dictionary of English v.0.48:
backgammon \back"gam`mon\, n. [Origin unknown; perhaps fr. Dan.
bakke tray + E. game; or very likely the first part is from
E. back, adv., and the game is so called because the men are
often set back.]
A game of chance and skill, played by two persons on a
"board" marked off into twenty-four spaces called "points".
Each player has fifteen pieces, or "men", the movements of
which from point to point are determined by throwing dice.
Formerly called tables.
[1913 Webster]
backgammon board, a board for playing backgammon, often
made in the form of two rectangular trays hinged together,
each tray containing two "tables".
[1913 Webster]