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

See also: undetected, unnoticed

• sea lawyer
• sea lettuce
• sea lily
• sea lion
• sea louse
• sea lyme grass
• sea mat
• sea mew
• sea mile
• sea milkwort
• sea moss
• sea mouse
• sea nymph
• Sea of Azof
• Sea of Azoff
• Sea of Azov
• Sea of Cortes
• Sea of Japan
• Sea of Marmara
• Sea of Marmora
• Sea of Okhotsk
• sea onion
• sea otter
• sea pea
• sea pen