Loon (noun)

1. A large aquatic bird found mainly in the northern hemisphere, typically having a black-and-white plumage and a yodeling call.
2. A crazy or eccentric person.

Origin:

Middle english: from old english lōn, of germanic origin; related to dutch loen and german löwe "lion".

Examples:

1. The loon's eerie call echoed across the lake at night.
2. He was called a loon for his eccentric behavior.
3. The loon swam gracefully across the water.
4. The loon's black and white plumage made it easy to spot on the water.
5. The loon's nest was built on a small island in the middle of the lake.