Micromillimeter and Metric linear unit

Micromillimeter noun - A metric unit of length equal to one billionth of a meter.

Metric linear unit and micromillimeter are semantically related. In some cases you can use "Metric linear unit" instead a noun "Micromillimeter".

Metric linear unit noun - A linear unit of distance in metric terms.

Micromillimeter and metric linear unit are semantically related. Sometimes you can replace term "Micromillimeter" with "Metric linear unit", this terms are similar.