Keyword Tool based on a single keyword

I’m looking for a Keyword software that will generate a massive list (probably over 100,000+ keywords) from a single keyword. The software must only focus on this one keyword.
This is a broad example but this is the best way I can explain it if I type in the letter "a" it would return all the keywords that contain the letter "a".
I don’t want the service to use the existing list and build onto. From the example above it it returned the keyword "Apple" I don’t want it to use this keyword to add on to the list, I just want it to focus on the letter "a".
If it uses MSN adcenters data that would be amazing too!

Original post by piwh1000