See je ne sais quoi in American Heritage Dictionary 4
(zhəˌ nə sā kwäˈ, sĕ)
noun
A quality or attribute that is difficult to describe or express: “Fishing has lacked a certain je ne sais quoi in terms of its public image, as all activities must that involve beer, worms and one-size-fits-all gimme caps”(Charles Leerhsen).