Learner's definition of GULF
1 : a large area of ocean that is partly surrounded by land — often used in proper names
— often used before another noun
the Gulf of Mexico
the Persian Gulf
They have a home on the Gulf Coast. [=the coast of the Gulf of Mexico]
the (Persian) Gulf region
the Gulf states [=the U.S. states next to the Gulf of Mexico or the countries next to the Persian Gulf]
2 : a difference between two people, groups, or things — often + between
The report examines the (widening) gulf [=gap, divide] between the state's rich and poor schools.
The program is intended to help bridge the gulf between younger and older generations.