1. in an exhaustive manner (Freq. 8) - we searched the files thoroughly • Syn: exhaustively • Derived from adjective: thorough 2. completely and absolutely ('good' is sometimes used informally for 'thoroughly')(Freq. 7) - he was soundly defeated - we beat him good • Syn: soundly, good • Derived from adjective: sound (for: soundly), thorough • Usage Domain: colloquialism