A monumental work edited by Charles Muller: http://www.buddhism-dict.net/ddb/

From the site introduction:

“This dictionary is a compilation of Buddhist terms, texts, temple, schools, persons, etc. found in Buddhist canonical sources. Its compilation was initiated in 1986 during my first semester of graduate school, upon my realization of the dearth of comprehensive English language reference works for Buddhist technical terminology. Since my basic area of interest was the Chinese Buddhist canon, the orientation of the dictionary has been toward East Asian sources, and therefore the dictionary was known during its first 15 years of existence as the Dictionary of East Asian Buddhist Terms (DEABT). Realizing, however, that a large portion of the content was actually concerned with Indian and other cultural manifestations of Buddhism, and not wanting to discourage potential collaborators with other orientations, we renamed it, in 2001, to the present Digital Dictionary of Buddhism (DDB). Thus, the content of this database/dictionary/encyclopedia/translation glossary is intended to be pan-Buddhist in character.”

-Charles Muller

Access is by free registration.