What does carbuncle mean?
A carbuncle is, in its dominant modern sense, a painful cluster of interconnected boils — a deep bacterial infection of the skin, usually caused by Staphylococcus aureus, in which several hair follicles become inflamed and fill with pus. It typically develops on thick-skinned areas such as the back of the neck, thighs, or shoulders, and may require drainage and antibiotics. The word also preserves an older meaning: a red garnet or similar gemstone polished into a smooth dome, believed since antiquity to glow like a live coal. Both senses descend from the same source, Latin carbunculus, 'little coal', which captures how a fiery jewel and a burning sore were imagined alike. Today the medical sense prevails, though the word retains literary colour, and it is often used figuratively to condemn ugly buildings — most memorably by Prince Charles in 1984, who dismissed a proposed extension as 'a monstrous carbuncle on the face of a much-loved and elegant friend'.
A large, painful cluster of boils; a deep bacterial infection of the skin in which several hair follicles form a single pus-filled mass.
"She needed surgery to drain the carbuncle that had formed at the base of her spine."
The standard plural is carbuncles.
A smooth-cut red garnet or similar gemstone, formerly believed to emit light like a glowing coal; occasionally extended to anything shining red.
"The crown was set with sapphires, emeralds, and a great central carbuncle."
Now largely confined to historical, heraldic, and literary writing.
Standard English plural, used for both the medical and the gemstone sense.
"Recurrent carbuncles can be a sign of an underlying immune problem."
When Prince Charles famously branded a proposed library extension 'a monstrous carbuncle on the face of a much-loved friend', he resurrected a 700-year-old word that once meant both a glowing red gem and a festering sore.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of carbuncle
Carbuncle comes from Latin carbunculus, literally 'little coal', a diminutive of carbo, 'coal' or 'charcoal'. It entered English in the Middle Ages, initially naming a red gemstone — probably a garnet — thought to smoulder with inner light. By the late fourteenth century the word had been applied to festering sores whose burning inflammation evoked the same image, and the medical sense gradually became dominant.
Related word forms
How carbuncle is actually used
In modern usage the word is almost exclusively medical, though it retains an old-fashioned, formal flavour even there — 'boil' or 'abscess' is more common in everyday speech. The gemstone sense survives mainly in historical, literary, and biblical contexts. Figuratively, calling a building a 'carbuncle' is a stinging architectural insult, made famous by Prince Charles's 1984 speech.
Easily confused with carbuncle
A furuncle is a single boil infecting one follicle, whereas a carbuncle is a deeper cluster of several interconnected boils.