The Collaborative International Dictionary of English v.0.48:

manger \man"ger\, n. [F. mangeoire, fr. manger to eat, fr. L.
   manducare, fr. mandere to chew. Cf. Mandible, Manducate.]
   1. A trough or open box in which fodder is placed for horses
      or cattle to eat.
      [1913 Webster]

            And she brought forth her firstborn son, and wrapped
            him in swaddling clothes, and laid him in a manger;
            because there was no room for them in the inn.
                                                  --Luke 2: 7
      [PJC]

   2. (Naut.) The fore part of the deck, having a bulkhead
      athwart ships high enough to prevent water which enters
      the hawse holes from running over it.
      [1913 Webster]

WordNet (r) 3.0 (2006):

manger
    n 1: a container (usually in a barn or stable) from which cattle
         or horses feed [syn: manger, trough]

Easton's 1897 Bible Dictionary:

Manger
   (Luke 2:7, 12, 16), the name (Gr. phatne, rendered "stall" in
   Luke 13:15) given to the place where the infant Redeemer was
   laid. It seems to have been a stall or crib for feeding cattle.
   Stables and mangers in our modern sense were in ancient times
   unknown in the East. The word here properly denotes "the ledge
   or projection in the end of the room used as a stall on which
   the hay or other food of the animals of travellers was placed."
   (See INN.)