Question

When all carpels are united is termed as?

Answer 1

Carpels united is called Gynoecium.

Answer 2

When all carpels are united, they are called Gynoceium.  

Gynoceium is a female reproductive part of the flower however it is not directly involved in producing female gametes however it produces megaspores which develops it to gametophyte and then produce eggs.

The word gynoceium mean woman in Greek. This term is commonly used for the female reproductive part of a plant.