Japanese Buddhism and Related Religions

Popularly known as the Mochizuki jiten, the Mochizuki Buddhist Dictionary is the best large dictionary.
It is the definitive source for all areas of East Asian Buddhist studies. Useful for its numerous citations of original sources-- Principally for research use, not quick reference. A Chinese index for vols. 1–6 is available. Note that vols. 1–7, 8, and 9–10 are indexed separately.

If the Mochizuki Dictionary is the best large dictionary, the Iwanami Buddhism Dictionary is the best small dictionary. Also available on CD-ROM.