To take bath.  Agni Puraan, 14, says that Snaan are of 6 types -
(1) Nitya Snaan (daily one to keep the body clean and pure);
(2) Naimittik Snaan (on special occasions, for some reason, such as for cleansing purpose);
(3) Kaamya Snaan (taken with some desire, such as to have a son or to get cured in some Teerth or somewhere etc);
(4) Kriyaang Snaan (as part of some ritual to get some merit required as per procedure);
(5) Malkarshan Snaan or Abhyaang Snaan (to clean oneself physically); and
(6) Kriyaa Snaan.

Then there are six types of secondary baths too (Gaun Snaan). These are - Mantra Snaan, Baum Snaan, Aagneya Snaan, Vaasaveeya Snaan, Divya Snaan and Maanas Snaan.

(2) There are some auspicious months in which people take bath before sunrise, in Teerth places or in special or ordinary rivers in special places, they worship specific Devtaa, listen to scriptures, light a lamp before the Deity (or for example at the root of Tulasee plant in Kaarttik month) - these baths are also called Snaan, such as Kaarttik Snaan, Maagh Snaan etc.

(3) To bathe. According to Bhavishya Puraan, 1/19, Snaan is called when 100 Pal (approximately 6 Kilograms and 20 Grams) water or Panchaamrit is used to bathe Devtaa. Abhyang Snaan is called when 25 Pal approximately 1 and 1/2 Kilogram) water is used to bathe. Mahaa-Snaan is called when 2,000 Pal (approximately 124 Kilogram) water is used to bathe - normally to bathe Devtaa's idol, this measurement is given in reference to bathe Soorya Bhagavaan.