Wane (verb)
wayn
(of the moon) have a progressively smaller part of its visible surface illuminated, so that it appears to decrease in size.
(of a state or feeling) decrease in vigour or extent; become weaker.
Old English wanian ‘lessen’, of Germanic origin; related to Latin vanus ‘vain’.
Example sentences
“The moon waxed and waned and the month flew by.”
“Her interest in him waned as she learned about his violent tendencies.”
