Osteoporosis: Thinning of the bones, with reduction in bone mass, due to depletion of calcium and bone protein. Osteoporosis predisposes a person to fractures, which are often slow to heal and heal poorly. It is most common in older adults, particularly postmenopausal women, and in patients who take steroids or steroidal drugs. Unchecked osteoporosis can lead to changes in posture, physical abnormality (particularly the form of hunched back known colloquially as dowager?s hump), and decreased mobility. Treatment of osteoporosis includes exercise (especially weight-bearing exercise that builds bone density), ensuring that the diet contains adequate calcium and other minerals needed to promote new bone growth, use of medications to improve bone density, and sometimes for postmenopausal women, use of hormone therapy.