kilometer definition by American Heritage Dictionary
noun Abbr. km
A metric unit of length equal to 1,000 meters (0.62 mile). See Table at measurement.
Usage Note: Although the pronunciation of kilometer with stress on the second syllable, (kĭ-lŏmˈĭ-tər), is often censured because it does not conform to the stress pattern in millimeter and centimeter (it originally came about by false analogy with barometer and thermometer), it continues to thrive in American English. In a recent survey, 69 percent of the Usage Panel preferred this pronunciation, while 29 percent preferred the pronunciation (kĭlˈə-mēˌtər).