The Collaborative International Dictionary of English v.0.48:

Ledger \Ledg"er\(l[e^]j"[~e]r), n. [Akin to D. legger layer,
   daybook (fr. leggen to lay, liggen to lie), E. ledge, lie.
   See Lie to be prostrate.]
   1. A book in which a summary of accounts is laid up or
      preserved; the final book of record in business
      transactions, in which all debits and credits from the
      journal, etc., are placed under appropriate heads.
      [Written also leger.]
      [1913 Webster]

   2. (Arch.)
      (a) A large flat stone, esp. one laid over a tomb. --Oxf.
          Gloss.
      (b) A horizontal piece of timber secured to the uprights
          and supporting floor timbers, a staircase,
          scaffolding, or the like. It differs from an intertie
          in being intended to carry weight. [Written also
          ligger.]
          [1913 Webster]

   Ledger bait, fishing bait attached to a floating line
      fastened to the bank of a stream, pond, etc. --Walton.
      --J. H. Walsh.

   Ledger blade,a stationary shearing blade in a machine for
      shearing the nap of cloth.

   Ledger line. See Leger line, under 3d Leger, a.

   Ledger wall (Mining), the wall under a vein; the foot wall.
      --Raymond.
      [1913 Webster]

WordNet (r) 3.0 (2006):

ledger line
    n 1: a short line; a notation for extending the range above or
         below the staff [syn: ledger line, leger line]