Medical Definition of bid (on prescription)
bid (on prescription): Seen on a prescription, bid means twice (two times) a day. It is an abbreviation for "bis in die" which in Latin means twice a day. The abbreviation bid is sometimes written without a period either in lower-case letters as "bid" or in capital letters as "BID" or with periods as "b.i.d." However it is written, it is one of a number of hallowed abbreviations of Latin terms that have been traditionally used in prescriptions to specify the frequency with which medicines should be taken.
Other examples include:
Last Editorial Review: 5/13/2016
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