Abbreviation for "colony forming units," a count of the number of active bacterial cells in preparations of Lactobacillus acidophilus and other "friendly" organisms of the digestive system. Counts as high as one billion CFU per gram are not uncommon
Russ Rowlett (Director), How Many? A Dictionary of Units of Measurement, Center for Mathematics and Science Education University of North Carolina, USA 2005. http://www.unc.edu/~rowlett/units/dictA.html, (Unit of Meas and Covr Factors - Amer) {608}