Question

why is it called menstruation not womenstruation?

Answer 1

A girl's first menstrual period is called a menarche (from the Greek word men = month + arkhe = beginning). After the menarche, ovulation does not usually occur with menstruation for approximately the first year to 18 months

So it is called Menstruation

Answer 2

Answer :

It's called menstruation not womenstruation because a girl's first period is known as "menarche".

A girl's first period or menstrual cycle begins between 12 and 15 years of age.

The Greek word "menarche" splits into two words as "men" which mean "month" and "arche" which mean "beginning".

Greek word => men+arche = month beginning.