wane (1) — ONAD

wane1 /wān, weɪn

▸ verb [no object] (of the moon) have a progressively smaller part of its visible surface illuminated, so that it appears to decrease in size.

▪ (especially of a condition or feeling) decrease in vigor, power, or extent; become weaker:

confidence in the dollar waned.

– PHRASES
on the wane
becoming weaker, less vigorous, or less extensive:

the epidemic was on the wane.

– ORIGIN Old English wanian ‘lessen’, of Germanic origin; related to Latin vanus ‘vain’.