M line may refer to: * M-line (mittel line or middle line), a structure in a muscle sarcomere * M Ocean View, a light rail and former streetcar line in San Francisco, California * McKinney Avenue Transit Authority, a streetcar line in Dallas, Texas also named the M-Line * M (Los Angeles Railway), a former streetcar service *Geometrisches Mittel, or

Geometric mean In mathematics, the geometric mean is a mean or average which indicates a central tendency of a set of numbers by using the product of their values (as opposed to the arithmetic mean which uses their sum). The geometric mean is defined as the ...

* M Line (Kintetsu), Japanese railwayline

See also