What does basophil mean?
A basophil is one of the least common types of white blood cell, belonging to the family of granulocytes alongside neutrophils and eosinophils. Its defining feature is coarse cytoplasmic granules that stain intensely with basic (alkaline) dyes such as haematoxylin, which is what gives the cell its name. Basophils normally account for well under 1% of circulating leukocytes, yet they play a disproportionate role in immunity: when activated during allergic reactions or inflammatory responses, they discharge histamine and other chemical mediators that drive symptoms like itching, swelling, and vasodilation. In clinical practice, doctors may measure the basophil count as part of a differential blood count; abnormally elevated levels can be associated with conditions such as chronic myeloid leukaemia or certain hypersensitivity disorders. The word is technical, appearing chiefly in medical literature, pathology reports, and immunology research.
nounA type of white blood cell (granulocyte) characterized by granules that stain readily with basic dyes; basophils play a role in inflammatory and allergic responses by releasing histamine and other mediators.
- A granular white blood cell that stains readily with basic dyes and releases histamine in allergic and inflammatory responses.
"The blood smear showed an elevated number of basophils, prompting the physician to investigate a possible allergic reaction."
"A high basophil count can occasionally point to a myeloproliferative disorder."
"When triggered by an allergen, the basophil releases histamine from its granules."
Standard English plural.
"Basophils are among the rarest cells seen on a routine blood smear."
Basophils make up less than 1% of your white blood cells, yet they're packed with histamine — the same chemical behind your hay fever and hives.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of basophil
The word derives from Greek roots: "basis" meaning base, and "-philos" meaning loving or fond of, so a basophil is literally a cell that loves or attracts basic dyes. It was coined in the late 19th century following Paul Ehrlich's pioneering work on blood-cell staining techniques, which revealed distinct classes of granulocytes based on their dye affinities. Cognates sharing the same suffix include eosinophil and neutrophil.
Related word forms
How basophil is actually used
Strictly a term of haematology and immunology; used almost exclusively in medical and scientific registers. The adjective form is "basophilic". Plural is "basophils".
Easily confused with basophil
An eosinophil is a different type of granulocyte whose granules stain with acidic dyes rather than basic ones, and it is more closely associated with parasitic infection and allergy.
A neutrophil is the most abundant white blood cell, staining neutrally, whereas a basophil is rarer and stains with basic dyes.