A nanometre (American spelling: nanometer; symbol nm) (Greek: νάνος, nanos, "dwarf"; μέτρον, metrοn, "unit of measurement")'s a unit of length in the metric system, equal to one billionth of a metre (for example, 10-9 m or one millionth of a millimetre). It's one of the more often used units for very small lengths, and equals ten Ångström, an internationally recognized non-SI unit of length. It's often associated with the fiel… (More on Nanometre)