Definition of “mean” - Learner’s Dictionary

mean

adjective uk us /miːn/
UNKIND

B2 unkind and unpleasant:

I thought my sister was being mean to me.
NOT GENEROUS mainly UK

B2 A mean person does not like spending money, especially on other people:

He's too mean to buy her a ring.
VIOLENT mainly US

A mean person or animal is strong and violent, and makes people frightened:

He's a big, mean guy.
GOOD [ always before noun ] informal

very good:

I make a mean spaghetti.
AVERAGE [ always before noun ]

In maths, a mean number is an average number:

Their mean age at death was 84.6.

(Definition of “mean adjective” from the Cambridge Learner's Dictionary © Cambridge University Press)