con‧spi‧ra‧to‧ri‧al /kənˌspɪrəˈtɔːriəl/
adjective1. a conspiratorial expression, voice, or manner suggests you are sharing a secret with someone:
His voice became low and conspiratorial. Pat whispered to Maggie in a conspiratorial tone.conspiratorial whisper/smile/wink etc Britta gave him a conspiratorial smile.2. relating to a conspiracy
—conspiratorially adverb [TahlilGaran] Dictionary of Contemporary English ▲