wiggle room

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

• noun Flexibility, as of options or interpretation.

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

• noun idiomatic The opportunity to make alternative decisions or to pursue other courses of action, especially any involving only minor changes to one's present situation or course.

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

• noun flexibility of interpretation or of options