subreptitious
/ˌsʌbrɪpˈtɪʃəs/adjective
1Chiefly Ecclesiastical Law. Obtained by subreption; involving or characterized by the suppression of truth or the concealment of facts.
2Secret; clandestine; = surreptitious.
Origin
Mid 16th century; earliest use found in Glasse of Truthe. From classical Latin subreptīcius (also surreptīcius; in post-classical Latin also subreptitius, surreptitius) stolen, kidnapped, in post-classical Latin also false, deceitful, taking place by stealth + -ous.