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

Thousands of volunteers showed up after a call went out about a soldier who needed a life-saving bone marrow transplant. Army Sgt. —Vanessa Etienne, People.com, 8 Apr. 2025

Some people have been cured by giving them bone marrow transplants from external donors, normally a close relative without sickle cell anemia, but the procedure does not always work, comes with a host of side effects and a risk of dying. —Victoria Forster, Forbes, 15 Mar. 2025

That will allow children to have bone marrow transplants in Connecticut rather having to travel to Boston or Philadelphia. —Sean Krofssik, Hartford Courant, 9 Mar. 2025

Megan Sykes, director of the Columbia Center for Translational Immunology in New York City, is tackling this by transplanting additional tissue from the donor’s immune system—either bone marrow cells or the thymus—into the recipient. —Amber Dance, Smithsonian Magazine, 7 Mar. 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