Bone matrix not yet calcified.
Immature bone that has not yet undergone calcification. [See: Fluoride & Osteoid | Fluoride & Osteomalacia
Uncalcified bone matrix, the product of osteoblasts.
Bone matrix which is unmineralized
Osteoid is a protein mixture which is secreted by osteoblasts. When it mineralizes, it becomes bone. Osteoid is primarily composed of Type I collagen.