Did I use the word deleterious right in this sentence? "Royce gave Frank a deleterious smile." I'm trying to write a short story and want to make sure I used this correctly.
This word is not used correctly in this sentence unless you mean something very out of the ordinary.
The word “deleterious” means “harmful” or “damaging.” We commonly say that something like smoking is deleterious to your health. Therefore, it would not be very usual to say that someone’s smile was deleterious. It would be possible to use the word if you were trying to show that Royce’s smile was injuring Frank. However, this is not a very common way to use the word and it might tend to confuse your readers.
So, this is grammatically correct, but “deleterious” is probably not the word you are looking for.