What is estrogen?

Answer 1

estrogen is a hormone that comprises a group of compound, including estrone, estradiol and estriol. Its the main sex hormone in women and is essential to the mentrual cycle.
The word you are looking for is Estrogen

Estrogen is a hormone that females have, Males have a hormone called testosterone. both Estrogen and testosterone help a person grow, make their mind more complex, grow taller, new muscles, for women become ready to have a baby, grow pubic hair (hair around the vagina, penis and armpits)

More detail:

Estrogen is a hormone that comprises a group of compounds, including estrone, estradiol and estriol. It is the main sex hormone in women and is essential to the menstrual cycle. Although estrogen exists in men as well as women, it is found in higher amounts in women, especially those capable of reproducing.

Estrogen contributes to the development of secondary sex characteristics, which are the defining differences between men and women that don't relate to the reproductive system. In women, these characteristics include breasts, a widened pelvis, and increased amounts of body fat in the buttock, thigh and hip region. Estrogen also contributes to the fact that women have less facial hair and smoother skin then men.
According to Britannica, estrogen is any hormone that "influences the female reproductive tract in its development, maturation, and function." If you would like to read more on it, here is the address: http://www.britannica.com/eb/article-9033102/estrogen
Oestrogen is a group of hormones that sexually develops the female body i.e. breast enlargement, menstruation etc.
it is a female reproductive hormone which maintains the lining of the uterus