Lexical archaisms are single archaic words or expressions used regularly in an affair (e.g. religion or law) or freely; literary archaism is the survival of archaic language in a traditional literary text such as a nursery rhyme or the deliberate use of a style characteristic of an earlier age—for example, in his 1960 novel The Sot-Weed Factor, John Barth writes in an 18th-century style.
An archaic word or sense is one that still has some current use but whose use has dwindled to a few specialized contexts, outside which it connotes old-fashioned language.
For example, the works of Shakespeare are old enough that some obsolete words or senses are encountered therein, for which glosses (annotations) are often provided in the margins.
Archaisms are most frequently encountered in history, poetry, fantasy literature, law, philosophy, science, technology, geography and ritual writing and speech.
Because they are things of continual discovery and re-invention, science and technology have historically generated forms of speech and writing which have dated and fallen into disuse relatively quickly.
The pronominal adverbs found in the writing of lawyers (e.g. heretofore, hereunto, thereof) are examples of archaisms as a form of jargon.
[4] Archaisms often linger in proverbs, "falling easier on the tongue",[5] and employing two of the four fundamental rhetorical effects, permutation (immutatio) and addition (adiectio).