unsui (Japanese). Literally meaning ‘clouds and water’, this term describes Ch'an or zen monks who, having achieved enlightenment (satori) after an initial period of training under their first master, take to the road in search of other masters. This is done in order to either test their awakening against them or deepen it with them. The term refers to their lack of a fixed abode during this period. Present-day usage also refers to simple beginner-monks.

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