Bioburden is normally defined as the number of bacteria living on a surface that has not been sterilized The term is most often used in the context of bioburden testing, also known as microbial limit testing, which is performed on pharmaceutical products and medical products for quality control purposes. Products or components used in the pharmace...
The number of contaminating microbes on a certain amount of material prior to that material being sterilised. ... (09 Oct 1997) ... 
Type: Term Pronunciation: bī′ō-ber′den Definitions: 1. Degree of microbial contamination or microbial load; the number of microorganisms contaminating an object.
population of viable microorganisms on an item (ref. ISO 11607:2003(E)).
bioburden The number of contaminating organisms found on a given amount of material prior to undergoing an industrial sterilization procedure.