1. Being apart from others; solitary.
2. Being without anyone or anything else; only.
3. Considered separately from all others of the same class.
4. Being without equal; unique.
1. Without others: sang alone while the choir listened.
2. Without help: carried the suitcases alone.
3. Exclusively; only: The burden of proof rests on the prosecution alone.
Synonyms: alone, lonely, lonesome, solitary
These adjectives describe lack of companionship. Alone emphasizes being apart from others but does not necessarily imply unhappiness: "The first lesson reading teaches is how to be alone" (Jonathan Franzen).
Lonely and lonesome usually connote painful awareness of being alone: "'No doubt they are dead,' she thought, and felt ... sadder and ... lonelier for the thought" (Ouida). "You must keep up your spirits, mother, and not be lonesome because I'm not at home" (Charles Dickens).
Solitary often stresses physical isolation that is self-imposed: I thoroughly enjoyed my solitary dinner.