Can you believe it? I had a great list of words that all go together, and someone stuck in a word that doesn't belong. Can you take it out for me?
I would say
All others are also nouns
Inject is the only one that can only be a verb
Because the others are all:
both nouns* and verbs, whereas "inject" is only a verb
* I thought "perfect" and "affect" weren't nouns either but the dictionary says they are
Another possible answer would be
as it is the only word that cannot
be made into a new word by 'ion' to the end.