Where can I download an English XML dictionary?

[ssfsx17]

The dictionary needs to:
1. Contain information on whether the word is a noun, verb, etc.
2. Store the words primarily as whole words in their original spelling. They cannot have pronunciation symbols.
3. Be supported at the present time and the foreseeable future.
4. Be either a flat TXT file with the words as the first column, or be an XML file where the words are the second-to-top level element type. Either that, or it must be possible to send a request / call a function using a whole word as the input and get back information on the word as output.

I want such a dictionary for a computer program that I am developing. I am NOT trying to use it for any personal purposes, such as looking up definitions or checking my own spelling.