obtained, done, made, etc., by stealth; secret or unauthorized; clandestine: a surreptitious glance.
2.
acting in a stealthy way.
3.
obtained by subreption; subreptitious.
Origin: 1400–50; late Middle English < Latin surreptīcius stolen, clandestine, equivalent to surrept(us), past participle of surripere to steal, (sur-sur-2 + rep-, combining form of rapere to snatch, rape1 + -tus past participle suffix) + -īcius-itious