People who are bad with words/have a limited vocabulary

People whose first language isn't English and people with intellectual disabilities are of course excluded from this.

But if you're a grown adult whose native language is English, and I can't get through a conversation with you in my natural vocabulary without you not knowing the meaning of perfectly common words, I'm probably gonna think you're a little stupid. Some words I've personally experienced people not knowing the meaning of:

-Conscientious -Slander -Malevolent -Ineloquent -Lecherous -Euphemism -Extroverted -Benevolence

Those are all pretty basic if you ask me. I think some people slept through English class in high school.