General words:
* Lonely: The most common and direct word.
* Solitary: Emphasizes being alone by choice.
* Isolated: Implies being physically or emotionally separated from others.
* Desolate: Suggests a feeling of emptiness and despair.
More specific words:
* Forsaken: Implies being abandoned or left behind.
* Alienated: Focuses on feeling disconnected from others.
* Lonesome: A more informal and melancholic term.
* Deserted: Implies being left alone, often by someone who was previously close.
* Heartbroken: Describes a specific type of loneliness caused by loss.
The best word to use will depend on the context and the specific feeling you want to convey.