conspiratorial

From conspiratory.

• IPA^(key): /kənˌspɪɹəˈtɔːɹɪəl/

conspiratorial (comparative more conspiratorial, superlative most conspiratorial)

1. Pertaining to conspiracy or conspirators.

   His conspiratorial whispers were soft, but that just attracted more attention.

   • 1960, P. G. Wodehouse, Jeeves in the Offing, chapter X:

     I pressed the button and he appeared, giving me, as he entered, the sort of conspiratorial glance the acting secretary of a secret society would have given a friend on the membership roll. “Oh, Swordfish,” I said, having given him a conspiratorial glance in return, for one always likes to do the civil thing, “this is Mr Herring, who has come to join our little group.”

• conspiratorially