A fancy term, usually used by formal businessmen and rich gentlemen, when they see "dat ass".

Mostly used during dinners party and high-class social gigs.

The two "n's" represent the ass.

Adj. Something that is expected to have a long lifespan by virtue of having existed for a long time, based on the lindy effect, named for the New York restaurant Lindy's, coined by Albert Goldman and popularized by Nassim Taleb.