Evanesce [ehv-uh-ness] is an verb meaning: "to dissipate, to become almost imperceivable, to be ephemeral, to vanish/disappear like vapor dispersing."
Here's a quick sentence using it:
*As a note, this term shows up after 1810, so you'll want to make sure it doesn't pop up in dialogue if your story's setting is before that.
What sentence might you construct using evanesce or one of it's forms? (evanescence, evanescible... ;-)
PS--If you're not writing romance, it's still okay to participate and leave a sentence here--we only grow stronger through sharing and learning from each other, right? :-)