restrict

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

• transitive verb To keep or confine within physical limits.
• transitive verb To prevent or prohibit beyond a certain limit or by restriction: synonym: limit.

from The Century Dictionary.

• To prevent (a person or thing) from passing a certain limit in any kind of action; limit; restrain.
• To attach limitations to (a proposition or conception), so that it shall not apply to all the subjects to which it would otherwise seem to apply: as, a restricted sense of a word.
• Synonyms Repress, etc. (see restrain), hedge in.

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

• transitive verb To restrain within bounds; to limit; to confine
• adjective obsolete Restricted.

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

• verb To restrain within bounds; to limit; to confine; as, to restrict worlds to a particular meaning; to restrict a patient to a certain diet.
• verb specifically, mathematics To consider (a function) as defined on a subset of its original domain.

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

• verb place limits on (extent or access)
• verb make more specific
• verb place restrictions on
• verb place under restrictions; limit access to