Metre/ˈmiːtər/ Definition 1 of 3Pro Tip 1/3SI Standard Understand that 'metre' is the standard SI unit for measuring length worldwide. The lab equipment is calibrated in metres. Pro Tip 2/3Metric Prefixes 'Metre' can combine with prefixes like 'kilo-' for 'kilometre' to denote larger lengths. The park is two kilometres long. Pro Tip 3/3Common Objects Relate 'metre' to everyday objects to grasp its size – about a guitar's length. He is taller than a metre, approximately like stacking two guitars.