bone marrow

noun

: a soft highly vascular modified connective tissue that occupies the cavities of most bones and occurs in two forms:

a

: one that is yellowish, consists chiefly of fat cells, and is found especially in the cavities of long bones

b

: one that is reddish, is the chief site of blood cell formation, and occurs in the normal adult in cancellous tissue especially of certain flat bones

called also red marrow

Examples of bone marrow in a Sentence

Recent Examples on the Web

Despite a battery of tests, including a contrast CT scan and bone marrow biopsy, experts could not determine what was making Jackie critically ill. — Lila Seidman, Los Angeles Times, 10 Aug. 2026

Your lymphatic system is an extension of your immune system and consists of lymph nodes, lymph vessels, bone marrow, and other tissues. — Sukhman Rekhi, Verywell Health, 10 Aug. 2026

Meanwhile, Jackie underwent advanced diagnostics, including a contrast CT scan and bone marrow biopsy. — Maddie Rhodes, USA Today, 10 Aug. 2026

On Wednesday afternoon Ojai Raptor Center provided an update, sharing that Jackie had a contrast CT scan, bone marrow biopsy, and other advanced diagnostics. — Laura Baisas, Popular Science, 5 Aug. 2026

Word History

First Known Use

1590, in the meaning defined above

Rhymes for bone marrow

• caballero
• mescalero
• aero
• faro
• garo
• narrow
• pharaoh
• sparrow
• taro
• bolero
• bracero
• estero

Kids Definition

bone marrow

noun

: a soft tissue rich in blood vessels that fills the cavities of most bones and occurs in two forms:

a

: one that is yellowish and fatty and is found especially in long bones (as the femur)

b

: one that is reddish, is the main place where blood cells are formed, and in adults is limited especially to certain flat or short bones (as the ribs)

Medical Definition

bone marrow

noun

: a soft highly vascular modified connective tissue that occupies the cavities and cancellous part of most bones and occurs in two forms:

a

: a whitish or yellowish bone marrow that consists chiefly of fat cells and is found especially in the cavities of the long bones

called also yellow marrow

b

: a reddish bone marrow that contains little fat, is the chief site of red blood cell and blood granulocyte formation, and occurs in the normal adult in cancellous tissue especially of certain flat bones

called also red marrow