The story
Blend of d(e)oxy- + oxy(tetra)cycline.
Etymology from Wiktionary, CC BY-SA 4.0.
doxycycline
Today it means: A broad-spectrum antibiotic C₂₂H₂₄N₂O₈ of the tetracycline class, which has a long half-life in the body and used orally to treat various bacterial infections. Full definition →