Glossary of linguistic terms by Eugene E. Loos (general editor), Susan Anderson (editor), Dwight H., Day, Jr. (editor), Paul C. Jordan (editor), J. Douglas Wingate (editor).
An excellent source for linguistic terminology.
If you have any interest in languages or linguistics you should give SIL International a visit.
BTW, the last update on the glossary page was in 2004 so if you can suggest some updates or additions, I am sure they would be appreciated.
Enjoy!