The name of one of the months on the Vulcan calendar. Although Vulcan possesses no moon by which to calculate the local passage of months, as is the practice on Earth, the mutual motions of Vulcan and its co-orbital world T'Khut are used to determine the length of Tasmeen and the other months on the Vulcan calendar.

In an alternate timeline inadvertently created by scientists studying history via the time portal known as the Guardian of Forever, Spock was killed by a wild le-matya on Vulcan's Forge on the 20th day of the Vulcan month of Tasmeen in the Vulcan year 8877 (2237 A.D. on the terrestrial Gregorian calendar).