noun

• (archaic, Thieves' Cant) A sweetheart; a prostitute or a mistress.
  "He did not relish the apparition of that Katherine, for when it appeared it seemed to bring with it a brother shadow that wore ragged clothes and tangled hair and foul linen, that drank from any flagon and drabbed with any doxy, that slept in tavern angles through hours of drunkenness, a thing whose fingers pillaged, filched, and pilfered when and where they could, a creature that once he saw whenever he stared into a mirror."

noun

• (colloquial) A defined opinion.
  "Orthodoxy is my doxy; heterodoxy is another man's doxy."

noun

• (informal, pharmacology) Clipping of doxycycline.
  "I know one patient who couldn't take the tabs but could tolerate liquid doxy."

noun

• (informal) A dachshund.