Webster's Revised Unabridged Dictionary · 1913

Dampen

Dampen (damp"'n) , transitive verb

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 , intransitive verb

To become damp; to deaden. — Byron