Endocentric compound

Endocentric compound is a type of compound in which one member functions as the head and the other as its modifier, attributing a property to the head. The relation between the members of an endocentric compound can be schematized as 'AB is (a) B'.

Example
The English compound steamboat as compared with boat is a modified, expanded version of boat with its range of usage restricted, so that steamboat will be found in basically the same semantic contexts as the noun boat. The compound also retains the primary syntactic features of boat, since both are nouns. Hence, a steamboatis a particular type of boat, where the class of steamboats is a subclass of the class of boats. See Exocentric compound.

Link
Utrecht Lexicon of Linguistics