moss-grown UK /ˈmɒsɡɹəʊn/US /ˈmɔsˌɡɹoʊn/ adjective2 •Having a covering of growing moss.In one spot distinguished by a moss-grown gothic monument, which retained the name of Queen's Standing, Elizabeth herself was said to have pierced seven bucks with her own arrows. — 1814 •(figurative) Old; old-fashioned, out of date. formsmore moss-grown · most moss-grown