Real Dictionary

osteoporosis
uncountable noun: Osteoporosis is a condition in which your bones lose calcium and become more likely to break.

osteoporosis in American English
a bone disorder characterized by a reduction in bone density accompanied by increasing porosity and brittleness, found chiefly in women who have passed menopause
noun: a disorder in which the bones become increasingly porous, brittle, and subject to fracture, owing to loss of calcium and other mineral components, sometimes resulting in pain, decreased height, and skeletal deformities: common in older persons, primarily

osteoporosis in British English
noun: porosity and brittleness of the bones due to loss of calcium from the bone matrix