The Collaborative International Dictionary
Tenthmeter
Tenthmeter \Tenth"me`ter\, Tenthmetre \Tenth"me`tre\, n. (Physics) A unit for the measurement of many small lengths, such that 10^ 10 of these units make one meter; the ten millionth part of a millimeter.
Wiktionary
tenthmeter
n. (context physics archaic English) A unit for the measurement of many small lengths, such that 1010 of these units make one meter; the ten millionth part of a millimeter.