Etymology

Adjective

1. Being in a state between dry and wet; moderately wet; moist.

   • O'erspread with a damp sweat and holy fear - John Dryden

2. Pertaining to or affected by noxious vapours; dejected, stupified.

   • 1667, All these and more came flocking; but with looks / Down cast and damp - John Milton, Paradise Lost, Book 1, ll. 522-3

Noun

1. Moisture; humidity; fog; fogginess; vapor.

   • Night . . . with black air Accompanied, with damps and dreadful gloom. - John Milton

2. Dejection; depression; cloud of the mind.

   • Even now, while thus I stand blest in thy presence, A secret damp of grief comes o'er my soul. - Joseph Addison
   • It must have thrown a damp over your autumn excursion. - James David Forbes

3. A gaseous product, formed in coal mines, old wells, pits, etc.

Verb

1. To dampen; to render damp; to moisten; to make humid, or moderately wet; as, to damp cloth.
2. To put out, as fire; to depress or deject; to deaden; to cloud; to check or restrain, as action or vigor; to make dull; to weaken; to discourage.
3. To suppress vibrations (mechanical) or oscillations (electrical) by converting energy to heat (or some other form of energy).

   • To damp your tender hopes - Mark Akenside
   • Usury dulls and damps all industries, improvements, and new inventions, wherein money would be stirring if it were not for this slug - Francis Bacon
   • How many a day has been damped and darkened by an angry word! - Sir John Lubbock
   • The failure of his enterprise damped the spirit of the soldiers. - Thomas Babington Macaulay
   • Hollow rollers damp vibration. - http://findarticles.com/p/articles/mi_hb3238/is_200004/ai_n7935204