Curmudgeon (noun)

1. An ill-tempered or surly person, especially an old one.
2. An old and difficult person, often one who is bad-tempered and grumpy.
3. A person who is easily angered and difficult to please.

Origin:

Early 17th century: from french coeur mechant "wicked heart", influenced by obsolete french méchant "wicked".

Examples:

1. The old man was a curmudgeon who never had anything nice to say.
2. He was known as a curmudgeon, always grumbling and complaining.
3. The curmudgeon was difficult to deal with, but his ideas were often insightful.
4. The curmudgeon was respected despite his surly manner.
5. The curmudgeon had a reputation for being difficult to work with.