What does bursa mean?
A bursa is a small, fluid-filled sac found in the human body at points where tissues move against each other, most commonly between tendons and bones near joints such as the shoulder, elbow, hip, and knee. Its purpose is to act as a natural cushion, reducing friction so movement remains smooth and painless. The word appears almost exclusively in medical, anatomical, and sports contexts; laypeople encounter it chiefly through 'bursitis', the painful inflammation of a bursa often caused by repetitive motion or prolonged pressure. The term comes ultimately from Greek and Latin words for a leather pouch or purse — an apt image, since the structure resembles a tiny bag of fluid. In formal writing the plural is usually the Latinized 'bursae', though 'bursas' is acceptable. Knowing the word helps patients understand common diagnoses involving joint pain, from housemaid's knee to tennis shoulder.
nounA small fluid-filled sac that cushions and reduces friction between moving structures in the body, such as a tendon and a bone.
- Anatomy: a small fluid-filled sac that reduces friction between tissues such as tendon and bone, found especially around joints like the shoulder, hip, and knee.
"Years of kneeling on hard floors inflamed the bursa over his kneecap."
"The MRI revealed an inflamed bursa beneath her acromion."
"Repeated pressure from tight shoes irritated the bursa behind his heel."
'Bursae' follows the Latin first-declension pattern and is preferred in formal medical literature; 'bursas' is the anglicized alternative seen in general usage.
"The surgeon noted inflammation in two separate bursae around the hip."
Your body carries dozens of tiny 'purses' of fluid — and when one gets angry, it earns its own medical name: bursitis.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of bursa
The word 'bursa' comes from medieval Latin 'bursa', meaning a purse or pouch made of hide, which itself derives from Greek 'byrsa' (hide, leather). The anatomical sense arose because the sac resembles a small bag of fluid. The same root gave English 'purse', as well as 'bursar', 'disburse', and 'reimburse', all originally concerned with money kept in a purse. The anatomical term entered scientific usage during the Renaissance era of anatomical description.
Related word forms
How bursa is actually used
Almost entirely confined to medical, anatomical, and sports-medicine contexts; rarely used in everyday conversation except through its derivative 'bursitis'. Plural forms are 'bursae' (Latinized, preferred in formal medical writing) or 'bursas' (anglicized).
Easily confused with bursa
A bursar is an administrator who handles finances at a college or school, whereas a bursa is a fluid-filled sac in the body.
A burse is a purse or a case for the corporal in church liturgy, while a bursa is an anatomical cushioning sac — both share the same 'purse' etymology.