A postfix is a letter or gathering of letters included toward the finish of a word which makes another word.
Regularly, the addition causes a spelling change to the first word. In the table over, the - e closure of confuse and make vanishes when the - particle addition is included.
Different cases of spelling changes include:
excellence, obligation + - ful → excellent, loyal (- y changes to I)
substantial, prepared + - ness → weight, preparation (- y changes to I)
capable, conceivable + - ity → capacity, probability (- le changes to il)
allow, discard + - particle → authorization, exclusion (- t changes to ss)
A decent student's lexicon will give you data on the right spelling of words with postfixes