Source : Webster's Revised Unabridged Dictionary (1913)

Dampen \Damp"en\, v. t. [imp. & p. p. {Dampened}; p. pr. & vb.
   n. {Dampening}.]
   1. To make damp or moist; to make slightly wet.

   2. To depress; to check; to make dull; to lessen.

            In a way that considerably dampened our enthusiasm.
                                                  --The Century.

Dampen \Damp"en\, v. i.
   To become damp; to deaden. --Byron.

Source : WordNet®

dampen
     v 1: smother or suppress; "Stifle your curiosity" [syn: {stifle}]
          [ant: {stimulate}]
     2: make moist; "The dew moistened the meadows" [syn: {moisten},
         {wash}]
     3: deaden (a sound or noise), especially by wrapping [syn: {muffle},
         {mute}, {dull}, {damp}, {tone down}]
     4: reduce the amplitude (of oscillations or waves)
     5: make vague or obscure or make (an image) less visible;
        "muffle the message" [syn: {deaden}, {damp}]
     6: check; keep in check (a fire)
     7: lessen in force or effect; "soften a shock"; "break a fall"
        [syn: {damp}, {soften}, {weaken}, {break}]