1. A metric unit of length equal to one billionth of a meter
   "The thickness of the coating was 50 millimicrons";
   - nanometer [US], nanometre [Brit, Cdn], nm, micromillimeter [US], micromillimetre [Brit, Cdn]

Derived forms: millimicrons

Type of: metric linear unit

Part of: micrometer[2] [US], micrometre [Brit, Cdn], micron

Encyclopedia: Millimicron