In a complete and comprehensive manner; with great attention to detail; exhaustively and carefully.
From Middle English, combining 'thorough' with '-ly'. 'Thorough' evolved from Old English 'thuruh' meaning 'through', which is related to the preposition 'through'. The transformation from spatial movement to completeness of action occurred in Middle English.
Unlike other words meaning 'completely', 'thoroughly' carries the unique implication of methodical process and careful attention to detail. When someone does something thoroughly, they don't just complete it - they go through it systematically, making 'thoroughly' the preferred adverb for describing meticulous work.
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