If someone is snotty, they have a lot of mucus coming out of their nose, usually because they are sick.
Being snotty is not very nice, and it can make people feel gross or uncomfortable.
Examples:
She has a snotty nose.
He is snotty because he has a cold.
The snotty baby needs a tissue.
I don't want to play with you if you're snotty!
His snotty nose was like a waterfall.
The snotty kid wiped his nose on his sleeve.