English has a huge lexicon, probably the largest word stock of the world’s living languages. As with all languages, some words in dictionaries carry the designation ‘obsolescent’, some ‘obsolete’, some ‘archaic’; and some are never (or very rarely) used in speech or writing. One such word is desuetude, a very good substitute for disuse, since it has a richer semantic range. But it has fallen into desuetude, just like malefactor, which is infinitely superior in every sense to the currently popular but utterly disposable phrases bad guy and bad actor. In this meaning field, evildoer is also superior to the latter two phrases and unwarrantedly neglected.
English vocabulary is unequalled for richness and eminently mineable for the most varied nuances of meaning that any writer or speaker might wish to express. Sad to say, however, words like malefactor and desuetude sleep the slumber of the dead in dictionaries, waiting only to be summoned into service by those who know of their existence and can exploit their aptness.