The Collaborative International Dictionary of English v.0.48:

Legerdemain \Leg`er*de*main"\ (l[e^]j`[~e]r*d[-e]*m[=a]n"), n.
   [F. l['e]ger light, nimble + de of + main hand, L. manus. See
   3d Leger, and Manual.]
   Sleight of hand; a trick of sleight of hand; hence, any
   artful deception or trick.
   [1913 Webster]

         He of legierdemayne the mysteries did know. --Spenser.
   [1913 Webster]

         The tricks and legerdemain by which men impose upon
         their own souls.                         --South.
   [1913 Webster]

WordNet (r) 3.0 (2006):

legerdemain
    n 1: an illusory feat; considered magical by naive observers
         [syn: magic trick, conjuring trick, trick, magic,
         legerdemain, conjuration, thaumaturgy, illusion,
         deception]