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: 1560–70; < Latinclandestīnus, equivalent to *clande,*clamde, variant of clam secretly (with -de adv. particle) + -stīnus, probably after intestīnus internal; see intestine