A name, category, or concept is said to be "empty" - a null set - if there are no really existing entities that correspond to it. →"emptiness."
Encyclopedia of Buddhism (Shakushi yōran, C. Shishi yaolan 釋氏要覽). A lexicon of Buddhist terms compiled by the Chinese monk Dōjō (C. Daocheng 道誠) in 1019.
Encyclopedia of Zen Monasticism (Zenrin shōkisen 禪林象器箋). A lexicon of Buddhist terms pertaining to Zen monastic practice compiled by the Japanese scholar monk Mujaku Dōchū 無著道忠 (1653-1744).