Stilbesterol is a synthetic nonsteroidal estrogen medication that is no longer used in human medicine due to its carcinogenic properties. However, there are several synonyms for this compound, including diethylstilbestrol (DES), stilboestrol, and stilbestrol. While these terms are considered interchangeable, DES is the most commonly used name in the medical community. Stilbestrol and stilboestrol are alternative spellings of the same drug, depending on regional differences in spelling. Despite its harmful effects, stilbesterol has historical significance as it was widely prescribed to pregnant women in the mid-20th century to prevent miscarriages and other pregnancy complications.