dampen

v. make damp, moisten, wet; become damp; moderate, depress, discourage, dull; diminish vigor, deaden; soundproof

Dampening, also damping, refers to the musical technique of muting an instrument while playing it, or soon after, before it has lost its sustain (stopped ringing). It can be used on a wide variety of string and percussion instruments. Dampening may be accomplished with a mute.
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Verb
1. smother or suppress; "Stifle your curiosity"
(synonym) stifle
(hypernym) suppress, stamp down, inhibit, subdue, conquer, curb
(hyponym) suffocate, choke
2. make moist; "The dew moistened the meadows"
(synonym) moisten, wash
(hypernym) wet
(hyponym) humidify, moisturize, moisturise
(derivation) dampener, moistener
3. deaden (a sound or noise), especially by wrapping
(synonym) muffle, mute, dull, damp, tone down
(hypernym) soften
4. reduce the amplitude (of oscillations or waves)
(hypernym) weaken
5. make vague or obscure or make (an image) less visible; "muffle the message"
(synonym) deaden, damp
(hypernym) damp, soften, weaken, break
6. check; keep in check (a fire)
(hypernym) check, retard, delay
7. lessen in force or effect; "soften a shock"; "break a fall"
(synonym) damp, soften, weaken, break
(hypernym) deaden, blunt
(hyponym) deafen

v. steam, vaporize

n. vapour, steam, mist (also vapor)

(v. t.)
To make damp or moist; to make slightly wet.
  

(v. t.)
To depress; to check; to make dull; to lessen.
  

(v. i.)
To become damp; to deaden.