Estrogen

Estrogens (AmE), or oestrogen (BE), are a group of compounds named for their importance in the estrous cycle of humans and other animals. They are the primary female sex hormones. Natural estrogens are steroid hormones, while some synthetic ones are non-steroidal. The name comes from the Greek οἶστρος (oistros), literally meaning "gadfly" but figuratively sexual passion or desire, and the suffix -gen, meaning "producer of".