When opening a terminal to hack in Fallout, fill all the available words into the field on the left (the case is not important, and one word per line). Once done, please start the process below on the right:
The "best" words are listed below, in blue background.
Insert one of the "best" words below into Fallout.
Fallout will react by giving the number of common letters.
In the selected "best" word, click on the sublist of words prefixed with that number in green background.