The unit “microgram” is pronounced as [ˈmaɪkrəʊɡræm]. For example, “This medicine contains 50 micrograms of a certain substance.” Here, “micrograms” is used to describe a very small amount. The prefix “micro-” means one millionth, and “gram” is the unit of mass. So, “microgram” refers to one millionth of a gram.