coot
UK[kuːt]US[kuːt]
n
A black or dark grey waterbird with a white bill and forehead.
n
(informal, chiefly North America) A foolish or eccentric person, typically an old man.
Etymology
The word 'coot' first appears in Middle English as 'cote'. Its origins are obscure but it is likely onomatopoeic, imitating the call of the bird. The term has been used for the aquatic bird since at least the 14th century. The humorous or derogatory slang sense of "a foolish person," especially an old man, emerged in the 18th century, drawing a comparison to the bird's somewhat awkward appearance and behavior.
Analysis
The word 'coot' is a simplex word of uncertain, possibly imitative origin. It functions as a single, unanalyzable morpheme in modern English.
Examples
A pair of coots were nesting in the reeds at the edge of the lake.
Don't mind him, he's just a silly old coot.
The American coot is easily identified by its white, chicken-like bill.