Archaism reflects language from a specific historical period; knowing the context helps comprehension. Reading Chaucer's work, one encounters numerous archaisms indicative of Middle English.
Pro Tip 2/3
Literary Charm
Writers may use archaisms intentionally to give a timeless charm to their work. Fantasy novels often use archaisms to create a sense of an ancient world.
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Not Everyday Speech
Archaism is rarely used in daily conversation; it's more common in literature or formal texts. He greeted us, 'Good morrow!', an archaism that sounded oddly formal today.