The Collaborative International Dictionary of English v.0.48:

Leman \Le"man\ (l[=e]"man or l[e^]m"an; 277), n. [OE. lemman,
   lefman; AS. le['o]f dear + mann man. See Lief, and Man.]
   A sweetheart, of either sex; a gallant, or a mistress; --
   usually in a bad sense. [Archaic] --Chaucer. --Spenser.
   --Shak.
   [1913 Webster]