An old word meaning 'formerly' or 'in the past'; used to refer to something that happened long ago.
From Old English 'ærest' meaning 'first' or 'earliest,' which evolved into 'erst' as a way to reference former times. Related to German 'erst' and Old High German 'erist.'
Shakespeare and other Renaissance writers loved 'erst' because it sounded beautifully archaic even then—it was old-fashioned 400 years ago, which is why it now sounds incredibly theatrical to modern ears.
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