* Some person.
_Is SOMEONE there?_
* Logically related to _anyone_, _everyone_, and _no one_. Becomes _no one_ via negation.
_Did ANYONE help with the clean-up effort?_
_Yes, SOMEONE helped yesterday, but NO ONE did today because EVERYONE was too busy._
* anybody, anyone, somebody
Some translation dictionaries have used the abbreviation _s.o._ or _so_ for _someone_.