(in prescriptions) make a mixture.
What’s The Origin Of The F-word?It's one of the most versatile words in the English language, but where did the F-word really come from? Originally, the naughtiest of naughty words was actually quite an acceptable word, though no English speaker would say that today.
Origin of f.m.
From the Latin word fīat mistūra
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019