Let's start...
I got exactly what you need. I have already worked over a "database-less" Dictionary website. It is not a problem at all.
I will provide you:
-> A web area where you can upload a word list (optionally, with the definition). If the definition is not provided, the script will find the definition over the Web and will add it to the dictionary database. (This will provide you an easy way to upload data to your dictionary, in future as well).
I also have a word list of approx. 50,000+ words. I can provide you that as well.
Let's work on it and I am sure we will fix what you need ASAP.