dasa-silmātā. A body of religious women in Sri Lanka whose status lies somewhere between that of laity and nuns. Their name means ‘the ten precept mothers’, a reference to the ten precepts they assume, being the same as the ten precepts for novice nuns (śrāmaṇerī) laid down in the Vinaya. Although, like nuns, they wear orange robes (cīvara) and shave their heads, they cannot receive full ordination because the ordination lineage for nuns has long been extinct in the Theravāda tradition.

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