A Dictionary of Islam: Being a cyclopedia of the doctrines, rites, ceremonies, and customs, together with the technical and theological terms, of the Muhammadan religion.

Read "A Dictionary of Islam: Being a cyclopedia of the doctrines, rites, ceremonies, and customs, together with the technical and theological terms, of the Muhammadan religion." by Hughes, Thomas Patrick for free. A classic public domain work covering islam -- dictionaries. Available in full text from Project Gutenberg.