Copse and Underwood

Copse noun - A thick patch of shrubbery, small trees, or underbrush.

Underwood and copse are semantically related In some cases you can use "Underwood" instead a noun "Copse".

Underwood noun - The brush (small trees and bushes and ferns etc.) growing beneath taller trees in a wood or forest.

Copse and underwood are semantically related in woods topic. You can use "Copse" instead a noun "Underwood", if it concerns topics such as underbrush, undergrowth, scrappy bushes.