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Estrogen isn't a molecule. It's a class of feminizing hormones, the most prominent of which is estradiol. Others include estrone and estriol. Collectively, these are called estrogens.
The masculinizing analog for estrogen is androgen (a word you practically never hear*), which also refers to a class of hormones. In addition to being the most well-known of the androgens, testosterone might be the most famous hormone in the whole body**. Dihydrotestosterone is actually the most potent androgen. Androsterone and Androstenedione are (relatively weak) others.
*e.g. It's such an androgen fest!
**Adrenaline is the only competitor that comes to mind.
This moment of pedantry was brought to you by TankieTanuki. 
Bro we have rules about what side your shirt has to button up depending on how your genitals look, none of it makes any fucking sense
What??
It's the same with belts in my experience. Men wear buckles pointing to the right and women to the left. (Requisite GENERALLY here. I'm obviously not going around getting up close and personal to peoples' waists).
What??