Isle
Examples of four letter compound words are:ontointoupon
4 with a small two in the corner
four
Manhattan Island
Three countries with the letter "A" appearing four times in their names are Madagascar, Albania, and Panama. Each of these names features the letter "A" repeated four times, making them unique in this regard.
It is "k." (A small island is a cay or key.)
key
A "bay" is a small protected body of water that is a four-letter word.
A four letter word for the noun brook is rill or a burn.
slit
A Wren.
twig
mesa
tiny
Tiny
Mesa
nick