stealthy
/ˈstel-thē/
adjective
slow, deliberate, and secret in action or character
intended to escape observation : furtive
designed to produce a very weak radar return
secret covert stealthy furtive clandestine surreptitious underhanded mean done without attracting observation. secret implies concealment on any grounds for any motive. covert stresses the fact of not being open or declared.