The chief or most extreme liar; someone notable for telling the greatest or most consequential lies.
From 'arch-' meaning 'chief' or 'extreme' and 'liar,' a term that appears occasionally in literature to describe particularly skilled or chronic deceivers.
The word 'archliar' appears in Paradise Lost when Milton describes Satan—the ultimate deceiver—and it perfectly captures how 'arch-' can mean not just 'first' but 'most extreme or skilled' at whatever you add it to.
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