restriction

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

• noun The action of restricting or the state of being restricted.
• noun Something that restricts; a regulation or limitation.

from The Century Dictionary.

• noun The act of restricting, or the state of being restricted; limitation; confinement within bounds: as, grounds open to the public without restriction.
• noun That which restricts; a restraint: as, to impose restrictions on trade.
• noun Reservation; reserve.
• noun In logic:
• noun The act of limiting a proposition by a restrictive particle.
• noun The inference from a universal to a particular proposition, or to one in which the subject is narrower while the predicate remains the same: as, all crows are black, hence some white crows are black. The example illustrates the danger of such inference.

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

• noun The act of restricting, or state of being restricted; confinement within limits or bounds.
• noun That which restricts; limitation; restraint.

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

• noun The act of restricting, or the state of being restricted.
• noun A regulation or limitation that restricts.

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

• noun a principle that limits the extent of something
• noun an act of limiting or restricting (as by regulation)
• noun the act of keeping something within specified bounds (by force if necessary)