A pin directly in back of another.
(also DOUBLE WOOD) When one pin is directly behind the other, such as the 1-5, 2-8 or 3-9.
a bet that has been left behind on the table while its owner has left the table behind in his rush to leave the game and, perhaps, the casino
a pin hidden from view by another pin
If you leave a spare where one pin is standing directly behind another, the rearmost pin is called the "sleeper".
when one pin is left standing behind another it is called a sleeper
A pin hidden behind another pin and not readily seen from the runway.