1. Not observed
   - unseen 
2. Not observed
   "managed to slip away unobserved"

See also: undetected, unnoticed

• schnitzel
• schnook
• schnorchel
• schnorkel
• schnorr
• schnorrer
• schnoz
• schnozzle
• Schoenberg
• schola cantorum
• scholar
• scholarly
• scholarly person
• scholarship
• scholastic
• scholastically
• scholasticism
• scholia
• scholiast
• scholium
• Schomburgkia
• Schonbein
• school
• school assignment
• school bell