Here's what GuruBlue posted this evening.
"From the Wikipedia
"irredentism is any position advocating annexation of territories administered by another state on the grounds of common ethnicity and/or prior historical possession, actual or alleged."
When the US "annexed" the Texas territory based on the fact that it was being settled by Americans, that would be irredentism."
Here's another definition.
Main Entry: ir·re·den·ta
Variant(s): also ir·ri·den·ta /"ir-i-'den-t&/
Etymology: Italian Italia irredenta, literally, unredeemed Italy, Italian-speaking territory not incorporated in Italy
: a territory historically or ethnically related to one political unit but under the political control of another."
Another example of irredentism is the Kurds in Iraq and Turkey. The Kurds are an ethnic group that have traditionally lived in the northern part of Iraq and southeastern Turkey. They'd like to be an independent nation, but are still governed by other nations. The Basques in northwestern Spain is another example of an ethnic group being ruled by another nation. The former Yugoslavia broke up because of irredentism -- ethnic groups being ruled by another ethnic group.