(in prescriptions) four times a day.
Origin of q.i.d.
From the Latin word quater in diē
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
quater in die (four times a day)
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.