chen-yen (Chinese). A Chinese Buddhist translation of the Sanskrit terms mantra and dhāraṇī. In the Chinese Buddhist context it refers to oral formulae of any length whose power resides in their sounds rather than their meanings, and which are usually phonetic reproductions of Sanskrit originals. Chinese characters were either adapted or invented in order to represent these sounds and preserve them in writing. These formulae are also referred to as chou, or spells.

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