'oestrogen' originates from Modern Latin/Greek, specifically the Greek word 'oistros', where 'oistros' meant 'gadfly, sexual passion' and the combining form '-gen' meant 'producer' or 'to produce'.

'oestrogen' was coined in the early 20th century as a Neo-Latin/scientific compound combining 'oestro-' (from Greek 'oistros') and '-gen'; the variant spelling 'estrogen' arose and became common in American English while 'oestrogen' remains common in British English.

Initially, the components referred to a 'stimulus' or 'passion' ('oistros') and 'producer' ('-gen'), but the scientific coinage came to mean 'a substance that produces or regulates female reproductive characteristics' and now denotes that group of steroid hormones.