1. Conducted with or marked by hidden aims or methods
   - clandestine, cloak-and-dagger, hole-and-corner, hugger-mugger, secret, surreptitious, undercover, underground

See also: covert

• cerebrum
• cerecloth
• cerement
• ceremonial
• ceremonial dance
• ceremonial occasion
• ceremonialism
• ceremonially
• ceremonious
• ceremoniously
• ceremoniousness
• ceremony
• Ceres
• ceresin
• Cereus
• ceria
• ceric
• ceriman
• cerise
• cerium
• cerivastatin
• cermet
• CERN
• cernuous
• cero