on the quiet (deception, general)

im Versteck (o) (deception)

heimlich (o) (deception)

im Geheimen (o) (deception)

hinter vorgehaltener Hand (o) (deception)

insgeheim (general)

unter der Hand (general)

en secret (o) (deception)

en cachette (o) (deception)

en douce (informal) (o) (deception)

segretamente (o) (deception)

di nascosto (o) (deception)

di soppiatto (o) (deception)

furtivamente (o) (deception)

en secreto (o) (deception)

a escondidas (o) (deception)

a urtadillas (o) (deception)

heimelijk (o) (deception)

stiekem (o) (deception)

in het geheim (o) (deception)

in het geniep (o) (deception)

i hemlighet (o) (deception)

i smyg (o) (deception)

förstulet (o) (deception)

secretamente (o) (deception)

às escondidas (o) (deception)

por baixo dos panos (slang) (o) (deception)