micromillimetre vs nanometer

micromillimetre and nanometer both are nouns.

Word	Noun	Adjective	Verb	Adverb
micromillimetre	Yes	No	No	No
nanometer	Yes	No	No	No

As nouns, micromillimetre and nanometer are synonyms defined as:

micromillimetre and nanometer: a metric unit of length equal to one billionth of a meter

Other synonyms of micromillimetre include micromillimeter, millimicron, nanometre, nm.

micromillimetre (noun)	nanometer (noun)
a metric unit of length equal to one billionth of a meter	a metric unit of length equal to one billionth of a meter