dampen

n. Moderate humidity; moisture; fogginess; moistness. [ 1913 Webster ]

v. t. [ imp. & p. p. dampened p. pr. & vb. n. dampening. ] 1. To make damp or moist; to make slightly wet. [ 1913 Webster ]

2. To depress; to check; to make dull; to lessen. [ 1913 Webster ]

In a way that considerably dampened our enthusiasm. The Century. [ 1913 Webster ]

v. i. To become damp; to deaden. Byron. [ 1913 Webster ]