adjective/sy.bʁɛp.tis/
surreptitious, furtive
Related: subrepticement
Learned borrowing from Latin subreptīcius, itself from the past participle of either subripiō (“to snatch away”) or subrēpō (“to creep under”). The adjective having in traditional court the sens of illicit, thus gaining the sense of something made furtively as in illicitly.