nanometer vs micromillimeter

nanometer and micromillimeter both are nouns.

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

As nouns, nanometer and micromillimeter are synonyms defined as:

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

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

nanometer (noun)	micromillimeter (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