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

Belmont hopes the findings will encourage clinicians to more carefully reassess antibiotic allergy labels, particularly in high-risk populations such as bone marrow transplant patients. —Jordan Shaked, Hartford Courant, 20 Feb. 2026

Viewers paid rapt attention to Robin Roberts’ journey through treatment tied to myelodysplastic syndrome, a bone marrow disease, in 2012, and, in 2023, kept up with Michael Strahan after his daughter was diagnosed with medulloblastoma, a type of brain tumor. —Brian Steinberg, Variety, 19 Feb. 2026

Right now, Acevedo is staying at the nonprofit’s current on-campus home while his 5-year-old stepdaughter recovers from a bone marrow transplant. —Michelle Marchante february 19, Miami Herald, 19 Feb. 2026

Customers can pick three tacos with chicken, beef, seafood or veggie fillings; an appetizer of chips and dip, chicharrones or corn with bone marrow butter; and for dessert, tres leches cake or churros with chocolate sauce. —Miguel Otárola, Denver Post, 18 Feb. 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