University of Pennsylvania
U Penn: Poetic Terms and Types
Click on these terms for an excellent definition of these poetic terms, some from the Oxford English Dictionary. Includes types of poetry as well as terms.
Other
Bob's Byway: Glossary of Poetic Terms
Calling itself "unique," Bob's is easy to use, with cross-links throughout, phonetic pronunciation guides when necessary, and many examples and quotations. Click on the letter and scroll for the word.