mother country

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun The country of one's birth or one's ancestors.
• noun The country from which the settlers of a territory originally came.

from The Century Dictionary.

• noun A country which has sent colonies to other countries: used in speaking of it in relation to its colonies.
• noun One's native country.
• noun A country as the mother or producer of anything.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun The country in which a person (or group of people) was born; motherland, homeland

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun the country where you were born