Other forms: dampened, dampening, dampens
To dampen is to make slightly wet, or to reduce enthusiasm. Dampen the cloth, dampen his spirits, nothing dampened the mood.
The figurative sense is the commoner one, and it is nearly always about spirits or enthusiasm. In engineering, damping is the removal of energy from a vibration, and it is what stops a car bouncing after a bump. Note damp beneath it.
1verbdampenTo make slightly wet.
“Dampen the cloth slightly before you wipe the leather.”
2verbreduceTo reduce enthusiasm.
“The rain did not dampen the fans' enthusiasm.”
dampen is a wetting, or a reducing.
Proto-Germanic
*dampaz
Old English
damp
Middle English
dampen — to stifle; suffocate
English
damp
English, today
dampen
From damp + -en. damp comes from Middle English dampen (“to stifle; suffocate”), from Old English damp, from Proto-Germanic dampaz. Akin to Low German damp, Dutch damp, and German Dampf (“vapor, steam, fog”), Icelandic dampi, Swedish damm (“dust”), and to German dampf imperative of dimpfen (“to smoke”). Also Middle English dampen (“to extinguish, choke, suffocate”).
Etymology from Wiktionary, CC BY-SA