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