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

See also: undetected, unnoticed

• energy of activation
• Energy Secretary
• energy state
• energy unit
• energy-absorbing
• energy-releasing
• energy-storing
• enervate
• enervated
• enervating
• enervation
• Enesco
• Enets
• enfant terrible
• enfeeble
• enfeeblement
• enfeebling
• enfeoff
• enfeoffment
• enfilade
• enfilade fire
• enfleurage
• enflurane
• enfold
• enfolding