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

The young serum triggered changes in bone marrow cells, leading them to secrete rejuvenating factors. —New Atlas, 10 Aug. 2025

Ong had been diagnosed with multiple myeloma, a rare type of bone marrow cancer. —Jonathan Burgos, Forbes.com, 4 Aug. 2025

The documentary marked the first time Scialfa publicly addressed getting diagnosed with multiple myeloma, a cancer of plasma cells, which are found in the bone marrow and are an important part of the immune system, according to the American Cancer Society. —Daniela Avila, People.com, 25 July 2025

This occurs due to bone damage from myeloma cells forming in the bone marrow. —Anna Giorgi, Verywell Health, 22 July 2025

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