An other, another (person, etc), more often rendered as another.
The other one; the second of two.
See other (determiner) below.
Alien.
Different.
Second.
To regard, label, or treat as an "other", as not part of the same group; to view as different and alien.
To treat as different or separate; segregate; ostracise.
Not the one or ones previously referred to.
A substitute; something that substitutes for another.
A substituendum; something to be substituted or replaced.