All of the approaches in this subthread are based upon graff's original statement about his interpretation of your problem:

OTOH, if you're looking for words that contain a particular pair of characters, and differ only in terms of using one vs. the other of those two (e.g. you really just want "bare/base", etc., but not "foot/fool"), you would probably want to use a regex like this ...

Having computed set of "matches" for each term you can choose to refine that such that they differ by only one character using the other approaches (bitwise OR, Levenshtein, etc) mentioned elsewhere in the thread.