suffix (something) onto (something else)
To add an affix onto the end of an existing word or stem in order to create a new word or an inflectional ending. The most common way to form the past tense is by suffixing "-ed" onto a verb. You can make certain nouns feminine by suffixing "-ette" onto the end of them.
suffix something onto something
to add an inflection or other part of a word onto another word. The students were told to suffix the correct plural marker onto all the nouns in the list. What do you get when you suffix -ed onto a verb like talk?