noun
gulf
GUHLF/ɡʌlf/
A large inlet of the sea partly enclosed by land.
Land encloses the gulf on three sides.

Etymology
Greek kolpos originally meant ‘bosom’ and also described a garment’s fold. The shared image is a curve or hollow, extended to the sea where land curves around an expanse of water.
In context
This area was covered by a vast inland sea. It existed for over 30 million years and stretched from Utah to Missouri and from the Gulf of Mexico to the Arctic Sea.