helly /ˈhɛ.li/adjective 1noun 1forms 2 adjective1 •(no longer used) Hellish, infernal.Then wavered all the rebel rings, And of a sudden, ere a single blow Was struck, precipitous they shrieking fled, And sought the portals of their Helly home. — 1892 noun1 •(slang, vulgar) Synonym of hell. formsmore helly · most helly