A barrel die is an uncommon type of die used most often by players of role playing games and wargames. It is similar to rolling logs.
Its shape is roughly cylindrical with between four and twenty flattened triangular facets, each numbered. Each triangular face alternates in alignment about 180 degrees. The two ends of the cylindroid are formed by half as many triangular facets as there are numbered faces, and are arranged so that it is impossible for the die to stop on one of its 'ends'.
There are six versions: 4, 6, 8, 10, 12, and 20 sides. They all have triangular faces except the 4 sided one, having rectangular faces much like a dreidel, and is also used in the traditional games daldøs and dayakattai. The 4 sided barrel die is easier to roll than the normal tetrahedral d4 used in most role-playing games.
A barrel die is rolled longitudinally so that one of the numbered faces comes to rest on top.
The cricket game "Owzthat" (relatively) popular in the 1960s-70s in England used barrel dice which were essentially short lengths of hexagonal bar (i.e. with 6 rectangular faces). The dice were rolled, rather than thrown, and there were no special precautions to prevent the dice landing or stopping end-on