Kilometre/kɪˈlɑːmɪtər/ Definition 1 of 1Pro Tip 1/3Measurement Units Often used with other units to describe area or speed. The car was going 80 kilometres per hour. Pro Tip 2/3Common Prefixes Combined with 'milli-', 'centi-', 'deci-' to indicate fractions of a kilometre. The track is 200 metres, or 0.2 kilometres long. Pro Tip 3/3Geographical Context Used to express distances between locations in many countries. The next town is 5 kilometres west of here.