Simplify the following text for a Grade 9 native English-speaking person.
Original: While technically the term is limited to the third largest party or third oldest party , it is common , though innumerate , shorthand for any smaller party .
Simplified: While the term should be used only when discussing the third largest party , it is often used to describe any smaller party . For example , in the United Kingdom a third party is a national political party other than the Conservative Party and Labor Party that has a presence in the House of Commons .