adjective

kept secret or done secretively, especially because illicit.

she deserved better than these clandestine meetings

secret,covert,furtive,surreptitious,stealthy,cloak-and-dagger,hole-and-corner,hole-in-the-corner,closet,behind-the-scenes,backstairs,back-alley,under-the-table,hugger-mugger,concealed,hidden,private,sly,sneaky,underhand,undercover,underground,black,hush-hush