The Collaborative International Dictionary of English v.0.48:
Privily \Priv"i*ly\, adv. In a privy manner; privately; secretly. --Chaucer. --2 Pet. ii. 1. [1913 Webster]WordNet (r) 3.0 (2006):
privily adv 1: confidentially or in secret; "told her friend privily that she was planning to be married"