Kalmar "micromillimeter" ba kalma ce da aka saba amfani da ita ba, amma tana iya yiwuwa tana nufin juzu'in ma'aunin tsayi ko nisa wanda yayi daidai da dubu ɗaya na millimita, ko kuma 0.001 millimeters. Wannan kuma ana kiransa da micrometer, ko µm, wanda aka fi amfani da shi a aikace-aikacen kimiyya da injiniya don kwatanta ƙananan tazara, kamar girman sel, ƙwayoyin cuta, ko ƙananan ƙwayoyin cuta.