clandestine

/klænˈdɛstɪn/
adjective
  1. Done secretly, especially because it is not allowed or is morally wrong.
    • They carried out a clandestine operation to smuggle supplies across the border.
    • The two lovers had a clandestine affair that no one knew about.
    • The spies arranged a clandestine meeting in an abandoned warehouse.
Antonyms
What does "clandestine" mean? | whatsthatwordmean | whatsthatwordmean