la rosquilla - ring-shaped pastry, doughnut
  roñoso - filthy, dirty, mean, rusty, miserly,...
  la ronda - song of endearment, group of...
  el romero, la romera - pilgrim
  el rascacielos - skyscraper
  el rasguño - scratch
  el querellante, la querellante - plaintiff in a legal action...
  quimérico - fanciful, highly improbable,...
  el quinceañero, la quinceañera - specifically, a 15-year-old, or, more...
  el quinqui, la quinqui - petty thief, delinquent, hoodlum
  el queso - cheese
  el quilate - carat, karat
  quizás, quizá - maybe, perhaps
  quirúrgico - surgical
  el quiosco - kiosk, newspaper stand, bandstand
  la quintaesencia - the ultimate or most typical instance...
  el quebradero de cabeza - headache in the sense of someone or...
  quienquiera - whoever
  a quemarropa - at point-blank range, extremely close
  el quehacer - task, something that needs doing, to-do