OBSOLETE, adj. No longer used by the timid. Said chiefly of words. A word which some lexicographer has marked obsolete is ever thereafter an object of dread and loathing to the fool writer, but if it is a good word and has no exact modern equivalent equally good, it is good enough for the good writer. Indeed, a writer's attitude toward "obsolete" words is as true a measure of his literary ability as anything except the character of his work. A dictionary of obsolete and obsolescent words would not only be singularly rich in strong and sweet parts of speech; it would add large possessions to the vocabulary of every competent writer who might not happen to be a competent reader.

What do you think it means?
This is from the Devil's dictionary.

Especially the last sentence.