Obsoletely is an adverb that means in an outdated or antiquated manner. There are several synonyms for this word, including antiquatedly, archaically, passe, outmodedly, and old-fashionedly. These words describe something that is no longer in use or relevant to modern times. Antiquatedly and archaically both refer to a method or manner of doing something that is no longer practical or useful. Passe and outmodedly describe something that is outdated or out of fashion. Old-fashionedly refers to a style or way of doing something that is no longer popular or fashionable. Using any of these synonyms for obsoletely illustrates that something is no longer suitable for modern times.