minor league

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

• noun A league of professional sports clubs that are not in the major leagues but are usually owned by or affiliated with major-league teams.

from the GNU version of the Collaborative International Dictionary of English.

• noun Sport) A league of professional sports teams less proficient than a major leagues. Players in the minor leagues generally are paid less than those in the major leagues, and their games attract less atention.

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

• noun An association of sports teams that plays at a level below the major leagues of a sport.
• adjective Having a quality less than the best possible.

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

• noun a league of teams that do not belong to a major league (especially baseball)