characterized by, done in, or executed with secrecy or concealment, especially for purposes of subversion or deception; private or surreptitious: Their clandestine meetings went undiscovered for two years.
Origin of clandestine
1560–70; < Latinclandestīnus, equivalent to *clande,*clamde, variant of clam secretly (with -de adv. particle) + -stīnus, probably after intestīnus internal; see intestine
Related formsclan·des·tine·ly, adverbclan·des·tine·ness, clan·des·tin·i·ty, nounun·clan·des·tine·ly, adverb
1560s, from Latin clandestinus "secret, hidden," from clam "secretly," from adverbial derivative of base of celare "to hide" (see cell), perhaps on model of intestinus "internal." Related: Clandestinely. As a noun form, there is awkward clandestinity (clandestineness apparently being a dictionary word).