<astronomy, instrument> An instrument for determining longitude by observation of the stars. ... Origin: F. Megametre. ... (29 Oct 1998) ... Found on http://www.encyclo.co.uk/local/20973
Me·gam'e·ter noun [ Mega- + -meter : confer French mégamètre .] (Physics) 1. An instrument for determining longitude by observation of the stars. 2. A micrometer. [ R.] Knight. Found on http://www.encyclo.co.uk/webster/M/41