osteoporosis

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

• noun A disease characterized by a decrease in bone mass and density, occurring especially in postmenopausal women, resulting in a predisposition to fractures.

from The Century Dictionary.

• noun Morbid absorption of bone proceeding from the Haversian canals, so that it becomes abnormally porous.

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

• noun (Med. & Physiol.) An absorption of bone so that the bone tissue becomes unusually porous. It occurs especially in elderly men and postmenopausal women, and predisposes the elderly to fractures of the bones.

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

• noun pathology A disease, occurring especially in women following menopause, in which the bones become extremely porous and are subject to fracture.

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

• noun abnormal loss of bony tissue resulting in fragile porous bones attributable to a lack of calcium; most common in postmenopausal women