\Me*gam"e*ter\, n. [Mega- + -meter: cf. F.
m['e]gam[`e]tre.] (Physics)
1. An instrument for determining longitude by observation of
   the stars.
2. A micrometer. [R.] --Knight.

\Meg"a*me`ter\, Megametre \Meg"a*me`tre\, n. [Mega- +
meter, metre, n., 2.]
In the metric system, one million meters, or one thousand
kilometers.