The Collaborative International Dictionary of English v.0.48:

Dank \Dank\, a. [Cf. dial, Sw. dank a moist place in a field,
   Icel. d["o]kk pit, pool; possibly akin to E. damp or to
   daggle dew.]
   Damp; moist; humid; wet.
   [1913 Webster]

         Now that the fields are dank and ways are mire.
                                                  --Milton.
   [1913 Webster]

         Cheerless watches on the cold, dank ground. --Trench.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Dank \Dank\, n.
   Moisture; humidity; water. [Obs.]
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Dank \Dank\, n.
   A small silver coin current in Persia.
   [1913 Webster]

WordNet (r) 3.0 (2006):

dank
    adj 1: unpleasantly cool and humid; "a clammy handshake";
           "clammy weather"; "a dank cellar"; "dank rain forests"
           [syn: clammy, dank]

Moby Thesaurus II by Grady Ward, 1.0:

18 Moby Thesaurus words for "dank":
   boggy, damp, dampish, dewy, fenny, humid, marshy, moist, muggy,
   rainy, roric, roriferous, sticky, swampy, tacky, undried, wet,
   wettish