What does the term "IBU" stand for?

The term "IBU" stands for International Bitterness Units, which is a scale used to measure the bitterness of beer. The measurement indicates the concentration of bittering compounds, primarily iso-alpha acids, that are extracted during the brewing process, particularly from hops.

This unit provides a way for brewers and consumers to understand the relative bitterness of different beer styles. For instance, a beer with a high IBU would typically be perceived as more bitter than one with a lower IBU, which is particularly relevant for styles that prominently feature hops, such as IPAs.

The other options do not accurately define IBU; they either suggest unrelated concepts or misinterpret the function of the term within brewing science. Thus, International Bitterness Units is the accurate and widely recognized terminology in the context of beer production and quality assessment.