What does "ledger" mean?

Ledger: (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.] Ledger bait, fishing bait attached to a floating line fastened to the bank of a stream, pond, etc. Walton. J. H. Walsh. -- Ledger line. See Leger line, under 3d Leger, a. -- Ledger wall (Mining), the wall under a vein; the foot wall. Raymond.