Archaic term for dice, literally 'one heaven, six earth', referring to the one and six pips on a die. Not used in everyday speech; modern Japanese uses サイコロ.
'Ittenchiroku' is one of the old names for dice.
Standard modern word for dice; 一天地六 is an archaic, literary synonym.
The name describes a die with the one face turned upward toward heaven and the six face downward toward the earth: 一天 “one toward heaven” and 地六 “six toward earth.”