Adhik Maas (extra lunar month)
Adhik Maas is an extra lunar month added roughly every 32 to 33 months to keep the Hindu calendar in step with the seasons. Devoted to Vishnu as Purushottam Maas, it is a month for prayer, not new ceremonies.
Also known as: Adhik Mas, Adhika Masa, Purushottam Maas, Mal Maas, Malmas, Leap month
Twelve lunar months come to about 354 days, some 11 days short of the solar year. When a lunar month passes without the Sun entering a new sign, with no Sankranti, it becomes an Adhik (extra) month and takes the name of the month that follows. So a year may have Adhik Shravana followed by the regular (nija) Shravana.
Because it lacks a Sankranti, the month was once called Mal Maas, ‘the impure month’, and set aside from ceremonies. Legend says Vishnu took it under his protection and named it Purushottam Maas, so it became a month for prayer, charity, scripture and pilgrimage. Weddings, griha pravesh, mundan, upanayana and new ventures are traditionally avoided.
Adhik Maas is not the same as Kharmas, though both are sometimes called Malmas. Kharmas comes twice every year, with the Sun in Sagittarius and Pisces; Adhik Maas is lunar and comes only every few years. Far more rarely, a lunar month holds two Sankrantis and a month is dropped (kshaya).