[noun] [U]Book early to avoid disappointment (= not being satisfied).To my (great) disappointment (= sadness), he decided to leave.A disappointment is something or someone that is not what you were hoping it would be.The party turned out to be a huge disappointment.I'm afraid I've been rather a disappointment to my parents.
DISAPPOINTMENT
Meaning of DISAPPOINTMENT in English
Cambridge English vocab. Кембриджский английский словарь. 2012