sur·rep·ti·tious 
(sûr′əp-tĭshəs)
(sûr′əp-tĭshəs)adj.
Obtained, done, or made by clandestine or stealthy means. See Synonyms at secret.
[Middle English, from Latin surreptīcius, from surreptus, past participle of surripere, to take away secretly : sub-, secretly; see SUB- + rapere, to seize; see rep- in the Appendix of Indo-European roots.]
sur′rep·titious·ly adv.
sur′rep·titious·ness n.