I am a linguist, and if you want to find good material about this subject do a search (in google, not cpan) for "morphology". This may not bring up results with code or canned algorithms, but it will give you a better understanding of what you should do. Finding the 'morphilogical root' of a word (in your example "host")requires more than knowing suffixes. For example, the root of "happiness" is "happy", here you don't just stick a suffix to a word, you first have to get rid of the "y". Therefore if you want to reverse the process and find the root of a given word, you can't always just hack off a suffix. Fortunately, these types of things follow pretty regular rules so you don't have to worry about a lot of exceptions (though you do have to acount for "foot" and "feet"). Small changes to the root itself are very common, so it will pay off in the long run if you take the time to make sure your algorithm does more then just hacking off suffixes.