An angle which is more than ${180}^{\circ }$ and less than ${360}^{\circ }$ is called:

The correct option is C reflex angle
By definition, we know, an angle which is more than ${180}^o$180∘ and less than ${360}^o$360∘ is called reflex angle.

That is, an angle larger than a straight angle but less than $1$ turn (between ${180}^o$ and ${360}^o$) are called reflex angle.

Therefore, option $C$ is correct.