The Collaborative International Dictionary of English v.0.48:

Coffer \Cof"fer\ (?; 115), n. [OF. cofre, F. coffre, L. cophinus
   basket, fr. Gr. ?. Cf. Coffin, n.]
   1. A casket, chest, or trunk; especially, one used for
      keeping money or other valuables. --Chaucer.
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            In ivory coffers I have stuffed my crowns. --Shak.
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   2. Fig.: Treasure or funds; -- usually in the plural.
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            He would discharge it without any burden to the
            queen's coffers, for honor sake.      --Bacon.
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            Hold, here is half my coffer.         --Shak.
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   3. (Arch.) A panel deeply recessed in the ceiling of a vault,
      dome, or portico; a caisson.
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   4. (Fort.) A trench dug in the bottom of a dry moat, and
      extending across it, to enable the besieged to defend it
      by a raking fire.
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   5. The chamber of a canal lock; also, a caisson or a
      cofferdam.
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   Coffer dam. (Engin.) See Cofferdam, in the Vocabulary.

   Coffer fish. (Zool.) See Cowfish.
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The Collaborative International Dictionary of English v.0.48:

Coffer \Cof"fer\, v. t.
   1. To put into a coffer. --Bacon.
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   2. (Mining.) To secure from leaking, as a shaft, by ramming
      clay behind the masonry or timbering. --Raymond.
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   3. To form with or in a coffer or coffers; to furnish with a
      coffer or coffers.
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WordNet (r) 3.0 (2006):

coffer
    n 1: an ornamental sunken panel in a ceiling or dome [syn:
         coffer, caisson, lacuna]
    2: a chest especially for storing valuables

Moby Thesaurus II by Grady Ward, 1.0:

54 Moby Thesaurus words for "coffer":
   Fort Knox, bank, bundle away, bursary, cache, cash register,
   cashbox, chest, coin box, deposit, depository, exchequer, file,
   fisc, gold depository, hutch, lay away, lay down, lay in,
   lay in store, locker, lodge, money chest, pack away, penny bank,
   piggy bank, pork barrel, public crib, public till, public treasury,
   public trough, put away, reposit, repository, reservoir, safe,
   safe-deposit box, salt away, salt down, stash, store, store away,
   storehouse, stow, stow away, stow down, strong room, strongbox,
   subtreasury, till, treasure-house, treasury, vault, warehouse



Easton's 1897 Bible Dictionary:

Coffer
   the receptacle or small box placed beside the ark by the
   Philistines, in which they deposited the golden mice and the
   emerods as their trespass-offering (1 Sam. 6:8, 11, 15).