Shakuni is the eighth karana and the first of the four fixed (sthira) karanas, which appear only once each in the lunar month, clustered around the new moon rather than rotating like the seven movable karanas. Shakuni falls on the second half of the fourteenth tithi of the waning fortnight, just before the new moon. Its name is linked to a bird, and the almanac tradition treats the fixed karanas of the dark of the Moon with caution, as periods suited to inward, dissolving, or ancestral matters rather than bright new beginnings. These are the conventions of the calendar tradition. The four fixed karanas exist because the sixty half-tithis of the month do not divide evenly among seven rotating names; the four fill the remaining positions around the conjunction of Moon and Sun.
Because shakuni is the ordinary Sanskrit word for a bird in general, some modern popular sources connect this karana's name to Shakuni, the cunning maternal uncle of the Kaurava princes in the Mahabharata, but the two are best kept separate: the epic character's name derives from the same common noun rather than the karana being named after him, and there is no textual basis in the muhurta literature for reading the epic Shakuni's scheming reputation into the karana's own character. As the first of the four fixed karanas, falling at the second half of the fourteenth tithi of the waning fortnight, Shakuni opens the run of karanas clustered around the new moon that the tradition treats with the same general caution given to the whole dark-of-the-Moon period.