What does bleb mean?
A bleb is a small blister or bubble — a localized swelling filled with fluid or air that forms on the skin, on a membrane, or on the surface of a material. The word appears most frequently in medical and scientific writing. Dermatologists use it for blister-like skin lesions, ophthalmologists for the raised pockets that form after glaucoma filtering surgery, and cell biologists for the rounded protrusions that emerge from a cell's membrane as it undergoes apoptosis, or programmed death. Outside technical use, a bleb can simply be a tiny bubble trapped beneath paint, glass, or another surface. The word carries no emotional connotation; it is neutral, precise, and largely confined to professional registers. Its diminutive, slightly whimsical sound belies its usefulness: few other English words so neatly capture the idea of a miniature blister, making 'bleb' a valuable term for anyone reading medical literature or describing fine-grained surface defects.
A small blister or bubble, especially one filled with fluid, forming on skin or on a surface.
"A tiny bleb rose where the mosquito had bitten him."
In medical usage, distinguished from larger blisters (bullae) by size.
In cell biology, a rounded protrusion of the plasma membrane, characteristic of cells undergoing apoptosis.
"Fluorescence microscopy revealed numerous blebs budding from the apoptotic cell."
Standard regular plural; used freely in both clinical and laboratory contexts.
"The biopsy showed multiple blebs scattered across the tissue sample."
Your own cells make blebs every day — when a cell undergoes apoptosis, it literally bubbles apart into membrane blebs before being tidily consumed.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does bleb come from?
The word 'bleb' first appears in English in the early seventeenth century, though its ultimate origin is uncertain; lexicographers have suggested it may be an expressive or imitative formation, possibly related to words like 'blob'. It has long served as a small-scale counterpart to 'blister' and 'bubble', and its adoption by pathology and later cell biology gave it a stable technical footing.
Related word forms
How bleb is actually used
Most common in medical, pathological, and cell-biological contexts; rare in everyday speech. In medicine, 'bleb' often refers to a raised blister-like lesion, such as those seen in bullous pemphigoid or after certain surgical procedures (e.g., filtration blebs after glaucoma surgery).
Easily confused with bleb
A 'blob' is any soft, shapeless mass, while a 'bleb' is specifically a small blister-like bubble or swelling.