oestrogen

the word 'oestrogen' is a modern scientific compound formed from greek roots. its first element, 'oestr-', derives from oistros, which originally meant a gadfly—an insect whose sting drives cattle to madness. this meaning extended metaphorically to signify a vehement impulse, frenzy, or strong desire. the second element, '-gen', comes from -genēs, meaning 'producer' or 'that which produces'. the term was coined in the early 20th century to name the hormone responsible for producing the physiological state of 'heat' or sexual receptivity (oestrus) in female mammals, thus linking the ancient concept of a frenzied drive to the modern biochemical agent that triggers the reproductive cycle.

Structure: oestr (gadfly, frenzy) + o (connective) + gen (producer) oestr- from greek oistros (gadfly, sting, frenzy), a connective vowel -o-, and -gen from greek -genēs (born of, produced by).