1. without anybody else or anything else

    Synonyms : solo, unaccompanied
    Examples :
    • the child stayed home alone
    • the pillar stood alone, supporting nothing
  2. without any others being included or involved

    Synonyms : entirely, exclusively, only, solely
    Examples :
    • the burden of proof rests on the prosecution alone
  3. lacking companions or companionship

    Synonyms : lone, lonely, solitary
    Examples :
    • he was alone when we met him
    • she is alone much of the time
  4. exclusive of anyone or anything else

    Synonyms : only
    Examples :
    • she alone believed him
    • cannot live by bread alone
  5. radically distinctive and without equal

    Synonyms : unequaled, unequalled, unique, unparalleled
    Examples :
    • he is alone in the field of microbiology
    • this theory is altogether alone in its penetration of the problem
  6. isolated from others

    Examples :
    • could be alone in a crowded room
    • was alone with her thoughts
    • I want to be alone