Tatpuruṣa

In Sanskrit grammar a tatpuruṣa (तत्पुरुष) compound is a dependent determinative compound, i.e. a compound XY meaning a type of Y which is related to X in a way corresponding to one of the grammatical cases of X.

There are many tatpuruṣas (one for each noun case, and a few others besides); in a tatpuruṣa, one component is related to another. For example, "boathouse" is a dative compound, a house for a boat. It would be called a caturthī-tatpuruṣa (caturthī refers to the fourth case — that is, the dative). The most frequent kind is the genitive tatpuruṣa. Examples are:-

The word "tatpuruṣa" is an example of the type: see in the list above.

Note: in Vedic Sanskrit rájaputra is a bahuvrihi and means "having a king as a son", and rajapútra is a tatpuruṣa and means "king's son": they are distinguished by the placing of the Vedic udātta accent.

...
Wikipedia