Lonely
Isolated
Synonyms: Isolated, all alone, companionless, with no one to turn to, forsaken, rejected, unwanted, sad, forlorn, lonesome, alone, friendless, without friends/companions, outcast, abandoned, unloved, unpopular, unhappy, and despondent.
Solitary
Synonyms: Solitary, alone, by oneself/itself, companionless, unaccompanied, lone, and without companions.
Deserted
Synonyms: Deserted, unfrequented, desolate, isolated, out of the way, sequestered, in the back of beyond, godforsaken, uninhabited, unpopulated, barren, remote, secluded, off the beaten track, in the middle of nowhere, and lone.
Example Sentences
He felt lonely in the crowd.
The empty house seemed very lonely.
She spends her evenings feeling lonely.
A lonely heart seeks companionship.