Sourpuss (noun)

1. A person with a sour or unpleasant attitude or facial expression.
2. A person who is always grumpy or negative.

Origin:

The word "sourpuss" is a combination of the words "sour" meaning having an acidic or bitter taste or attitude, and "puss" which is a slang term for a person"s face, especially when it is considered to be unattractive or unpleasant, therefore it refers to a person with a sour or unpleasant attitude or facial expression.

Examples:

1. She had a sourpuss expression on her face all day.
2. He was always a sourpuss and never had anything nice to say.
3. The sourpuss was unhappy with the way the meeting was going.
4. The sourpuss was in a foul mood and no one wanted to be around him.
5. The sourpuss attitude was draining the energy out of the room.