By oneself, solitary.
I can't ask for help because I am alone.
Apart from, or exclusive of, others.
Jones alone could do it.
Considered separately.
Without equal.
Unique; rare; matchless.
By oneself; apart from, or exclusive of, others; solo.
She walked home alone.
Without outside help.
The job was too hard for me to do alone.
Exclusively.
The responsibility is theirs alone.