The medical abbreviation "b.i.d." is short for the Latin phrase "bis in die," which means "twice per day" when taking prescription medication, according to MedicineNet. On some prescription labels, the term is written "bid" without periods or in all capital letters like "BID" on the bottle. Similar abbreviations include q.d., t.i.d., q.i.d. and q_h.
The abbreviation "q.d." is short for once per day or "quaque die" in Latin. MedicineNet reveals that "t.i.d." means three times per day or "ter in die" in Latin. The phrase four times a day is "quater in die" in Latin or "q.i.d." These abbreviations are also written without periods or as all capitals. Yet another denotation is "q_h" that stands for "quaque" and then the number of hours between doses. For example, "4 caps q6h" means take four capsules every six hours. The empty space between letters allows doctors to input a number.
MedicineNet explains these abbreviations stand for traditional Latin phrases that doctors and pharmacists originally used to fill prescriptions for patients to delineate how often medications should be taken. Other prescription abbreviations include "p.c.", which means after meals, "a.c.", which denotes before meals and "prn." for "as needed." The University of Minnesota Duluth explains the letters "q.o.d." tell patients to take the medicine every other hour.