What are the best answers for “a metric unit of length equal to one billionth of a meter”?

millimicron, nanometer, nanometre.

How many letters does the top answer for “a metric unit of length equal to one billionth of a meter” have?

The most common answer is millimicron (11 letters).

3 answers found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).

millimicron 11 letters wn-def

a metric unit of length equal to one billionth of a meter

nanometer 9 letters wn-def

a metric unit of length equal to one billionth of a meter

nanometre 9 letters wn-def

a metric unit of length equal to one billionth of a meter

a metric unit of length equal to one hundredth of a meter 75% similar → centimeter, centimetre, cm

a metric unit of length equal to one tenth of a meter 75% similar → decimeter, decimetre

a metric unit of length equal to one thousandth of a meter 75% similar → millimeter, millimetre, mm

a metric unit of length equal to 100 meters 71% similar → hectometer, hectometre, hm

a metric unit of length equal to 1000 meters (or 0.621371 miles) 63% similar → kilometer, kilometre, klick

a metric unit of length equal to ten meters 63% similar → decameter, decametre, dekameter