DuckCorp Dico

Found one definition

1.                 From The Collaborative International Dictionary of English v.0.48:
                   
   
   
                   
                     
   L \L\, a.
      1. Having the general shape of the (capital) letter L; as, an
         L beam, or L-beam.
         [Webster 1913 Suppl.]
      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.]
         [Webster 1913 Suppl.]