Carat and Unit of measurement

Carat noun - The unit of measurement for the proportion of gold in an alloy; 18-karat gold is 75% gold; 24-karat gold is pure gold.

Unit of measurement and carat are semantically related. In some cases you can use "Unit of measurement" instead a noun "Carat".

Unit of measurement noun - Any division of quantity accepted as a standard of measurement or exchange.

Carat and unit of measurement are semantically related. Sometimes you can replace term "Carat" with "Unit of measurement", this terms are similar.