adj

• (figuratively) Despondent; dispirited, downcast.
  "27 July 2016, Jane O’Faherty in The Irish Independent, Monarchs and prison officers win big on second race day Though Travis's 'Why does it always Rain on Me' boomed around the stands, there were few damp spirits in Galway on day two of the races."

noun

• (archaic) Fog; fogginess; vapor.
  "Night […] with black air / Accompanied, with damps and dreadful gloom."
• (archaic) Dejection or depression; something that spoils a positive emotion (such as enjoyment, satisfaction, expectation or courage) or a desired activity.
  "Ev’n now, while thus I stand blest in thy Presence, / A secret Damp of Grief comes o’er my Thoughts,"
• (mining, archaic or historical) A gaseous product, formed in coal mines, old wells, pits, etc.
  "There are sulphurous Vapours which infect the Vegetables, and render the Grass unwholsom to the Cattle that feed upon it: Miners are often hurt by these Steams. Observations made in some of the Mines in Derbyshire, describe four sorts of those Damps."

verb

• (transitive) To suppress vibrations (mechanical) or oscillations (electrical) by converting energy to heat (or some other form of energy).
  "Hydraulic shock absorbers are used to damp out vertical and lateral oscillations."
• (transitive, archaic) To dampen; to make moderately wet.
  "to damp cloth"
• (transitive, archaic) To put out, as fire; to weaken, restrain, or make dull.
  "How many a day has been damped and darkened by an angry word!"

noun

• (immunology) Initialism of damage-associated molecular pattern.
• (psychiatry) Acronym of deficits in attention, motor control and perception.