L \L\, a.

1. Having the general shape of the (capital) letter L; as, an L beam, or L-beam.

2. Elevated; -- a symbol for el. as an abbreviation of elevated in elevated road or railroad. -- n. An elevated road; as, to ride on the L. [Colloq., U. S.]

Source: Webster's Revised Unabridged Dictionary (1913)