The story
From de(s)me(thyl) + chlo(rtetra)cycline.
Etymology from Wiktionary, CC BY-SA 4.0.
demeclocycline
Today it means: A broad-spectrum tetracycline antibiotic produced by an actinomycete Kitasatospora aureofaciens and used especially in the form of its hydrochloride C₂₁H₂₁ClN₂O₈·HCl. Full definition →