The name given to a bhikkhunÄ«, who, so Ä€nanda tells UdÄyÄ«, came to see him at the Añjanavana in SÄketÄ. The nun asked him for what purpose the Buddha requested that samÄdhi should be practised and Ä€nanda answered that it was for the purpose of obtaining insight (A.iv.427f).
The Commentary (AA.ii.812) says that the bhikkhunī was so called because she came from a city called Jatilagaha.