noun
micrometre; micron
SI unit of length equal to one millionth of a metre. Commonly used in science and engineering; the symbol is µm.
このバクテリアの大きさは約2マイクロメートルです。
This bacterium is about 2 micrometres in size.
From English 'micrometre', itself from French 'micromètre', combining micro- (small) and metre.