surreptitious

Etymology

Borrowed from Latin surrēptīcius (“furtive, clandestine”), from surrēpō (“to creep along”).

adj

1. Stealthy, furtive, well hidden, covert (especially movements).
   He read the letter aloud. Sophia listened with the studied air of one for whom, even in these days, a title possessed some surreptitious allurement. 1922, Ben Travers, chapter 1, in A Cuckoo in the Nest
   It is also worth noting the case law on prisoners' correspondence which establishes that interception of a person's communications need not be surreptitious in order to amount to an interference with respect to Art 8 (1) [ECHR]. 1998, Lee A. Bygrave, “Data Protection Pursuant to the Right to Privavy in Human Rights Treaties”, in International Journal of Law and Information Technology, volume 6, number 3, pages 260–261