solitary

One who lives in solitude.

Confinement of a prisoner in isolation from other prisoners.

“he was held in solitary”

Of plants and animals; not growing or living in groups or colonies.

“solitary bees”

Lacking companions or companionship.

“a solitary traveler”

Characterized by or preferring solitude.

“a man of a solitary disposition”

“a solitary walk”

Devoid of creatures.

“a solitary retreat”

Being the only one; single and isolated from others.

“a solitary instance of cowardice”

“a solitary speck in the sky”