Jōshin 

1. (d. 1157). A Tendai monk who specialized in esoteric studies and ritual, and was one of Eisai's (1141-1215) first teachers.

2. A Sino-Japanese Buddhist term meaning ‘pure mind’, which indicates the inherently pure mind with which all beings are endowed (Chinese, ching hsin).

3. A Sino-Japanese Buddhist term meaning ‘eternal body’, or the body of a perfectly enlightened Buddha, which is opposed to the impermanent body of beings still trapped in saṃsāra (Chinese, ch'ang-shen).

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