Meaning of “sad” - Learner’s Dictionary

sad

adjective uk us /sæd/ (sadder, saddest)
NOT HAPPY

A1 unhappy or making you feel unhappy:

I was very sad when our cat died.
a sad book/movie
[ + that ] It's a bit sad that you'll miss our wedding.
[ + to do sth ] I was sad to see him go.
NOT SATISFACTORY [ always before noun ]

not pleasant or satisfactory:

The sad truth is that we've failed.
NOT FASHIONABLE UK informal

boring or not fashionable:

You enjoy reading timetables? You sad man!
sadness noun [ U ]

B2

We could see the sadness in their faces.

(Definition of “sad” from the Cambridge Learner’s Dictionary © Cambridge University Press)