compartment

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

• noun One of the parts or spaces into which an area is subdivided.
• noun A separate room, section, or chamber.
• transitive verb To compartmentalize.

from The Century Dictionary.

• noun A division or chamber in any part of a plant or of an animal.
• noun In forestry, the unit of area treated in a working plan. The size and the shape of compartments are determined mainly by topographic features.
• noun A part separated from the adjoining parts by a partition or other mechanical means: as, the compartments of a steamship or of a European railway-carriage.
• noun In art, a panel; a cartouche; a coffer; any portion of a work or design separated from the rest by a frame or molding, by being raised or sunk, or in any other way, especially to receive an inscription or a decoration of any kind: as, the compartments of a coffered ceiling; the small sculptured compartments of the portals of the cathedral of Amiens. See cut under calendar.
• noun Specifically, in heraldry, any partition or division of the field.

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

• noun One of the parts into which an inclosed portion of space is divided, as by partitions, or lines.
• noun (Shipbuilding) One of the sections into which the hold of a ship is divided by water-tight bulkheads.

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

• noun A room, or section, or chamber
• noun One of the parts in which an area is subdivided.
• noun biochemistry Part of a protein that serves a specific function.

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

• noun a partitioned section, chamber, or separate room within a larger enclosed area
• noun a space into which an area is subdivided