In geometric measurements, length most commonly refers to the longest dimension of an object. In some contexts, the term "length" is reserved for a certain dimension of an object along which the length is measured.
Applicable units are those of quantitykind:Length
http://en.wikipedia.org/wiki/Length
https://cdd.iec.ch/cdd/iec61987/iec61987.nsf/ListsOfUnitsAllVersions/0112-2---62720%23UAD072
http://dbpedia.org/resource/Length
In geometric measurements, length most commonly refers to the longest dimension of an object. In some contexts, the term "length" is reserved for a certain dimension of an object along which the length is measured.