Desanā Mahājāti. A ceremony popular in the Theravāda countries of south-east Asia such as Burma, Thailand, and Laos, involving the ritualized preaching of the Vessantara Jātaka. The ceremony takes place around one month after the planting of the rice crop and is regarded as an important opportunity to make merit (puṇya). It is commonly linked to the festival of Loi Krathong.

A Dictionary of Buddhism, Oxford University Press, 2003, 2004 (which is available in electronic version from answer.com)