Measurements, quantities and units (from the Greek nanos - dwarf), a prefix attached to the name of a unit of a physical quantity to form the name of a submultiple unit equal to 10-9 of the original unit. Symbol: n. Example: 1 nm (nanometre) = 10-9 m. Encyclopedia by letter A B C D E F G H I J K L M N O P Q R S T U V W Y Z