The female structure of a flower can be made up of a single carpel or two or more fused carpels is called a

Pistil

A Pistil is regarded as the female reproductive part of the flower. A pistil may consist of one or more ovule-bearing units called carpel. Carpels are collectively called gynoecium. When a pistil contains a single carpel, it is called a simple pistil but when it contains two or more fused carpels, it is called a compound pistil.