adverb; also archaic/poetic adjective meaning 'sudden'
Etymology. From Old Church Slavic vъdrugъ, literally 'at one stroke' or 'at one blow'; composed of v- (preposition 'in/at') + drugъ (a derivative of друг 'friend' or an old word for 'blow/stroke'). The concrete sense of a single sudden action evolved into the temporal meaning of abruptness.
Dictionary entry by Claude.
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