Pick some other Funk, Wagnall

This word is so wrong; in the first place, you'd never use "old" OR this word when referring to a woman. To use both would be a death wish. I wouldn't use the synonym of "ancient" either, unless you really like getting whacked with a handbag knitted during the Truman administration.

"Canescent" would be fine, make her think she's "glowing hot", like "incandescent".

Come to think of it, THAT might get you whacked by that old bag with that ancient handbag, too.