Stilbestrol

Stilbestrol, or stilboestrol, also known as 4,4'-dihydroxystilbene or 4,4'-stilbenediol, is a stilbenoid nonsteroidal estrogen and the parent compound of a group of more potent nonsteroidal estrogen derivatives that includes, most notably, diethylstilbestrol. The term "stilbestrol" is often used incorrectly to refer to DES, but they are not the same compound.
Stilbestrol itself is an active estrogen but is less potent than DES and other derivatives.

Stilbestrol derivatives

The stilbestrol estrogenic drugs include the following:

Of the stilbestrol estrogens, diethylstilbestrol, hexestrol, and benzestrol are the most well-known.

The stilbestrol estrogens bind with high affinity to both ERα and ERβ.

Estrogens closely related to the stilbestrols include paroxypropione and the anise and fennel-derived compounds anol, dianol, anethole, dianethole, and photoanethole. The triphenylethylene group of estrogenic drugs that includes triphenylethylene itself, estrobin, chlorotrianisene, broparestrol, ethamoxytriphetol, clomifene, tamoxifen, and more recently developed derivatives is also very closely related structurally to the stilbestrols.
Resveratrol is a stilbenoid with estrogenic properties that is not technically a stilbestrol derivative.

Occupational exposure to stilbestrol has resulted in gynaecomastia in workers.