qd (as on a prescription):
qd (sometimes written QD or q.d.) means one a day (from the Latin quaque die).
q_h (as on a prescription):
From the Latin word "quaque (once) and "h" for number of hours. So, for example, if a medicine is to be taken every 6 hours, it is written "q_h 6".
Quality of Life:
An increasingly important consideration in medicine. The goals of treatment are to reduce symptoms and improve quality of life.