A disease occurring among adults that is characterized by softening of the bones due to loss of bone mineral. Osteomalacia is characteristic of vitamin D deficiency in adults, while children with vitamin D deficiency suffer from soft and deformed bones (rickets). Many of the effects of the disease overlap with the more common osteoporosis, but the two diseases are significantly different. Osteomalacia is specifically a defect in mineralization of the protein (collagen) framework.