What does aculeus mean?
An aculeus is a sharp, pointed structure — a prickle, spine, or sting — found on certain plants and animals. The word is most familiar today in entomology, where it names the specialized organ with which bees, wasps, and their relatives deliver venom: technically a modified ovipositor, which is why only females can sting. In botany it may describe a stiff, needle-like prickle on a stem or leaf. Borrowed directly from Latin, where it meant a sting or sharp point, the word has kept both its form and its technical character, appearing almost exclusively in scientific writing rather than casual conversation. Its plural is usually the Latinate 'aculei'. Though rare outside specialist contexts, it rewards anyone interested in the precise vocabulary of natural history, and it connects etymologically to a whole family of 'sharp' words, including acute, acumen, and acupuncture.
nounA sharp point, prickle, or sting; in entomology, specifically the modified ovipositor used by bees and wasps to sting.
- A sharp point, prickle, or thorn, especially on a plant or animal.
- In entomology, the modified ovipositor that serves as the sting of bees, wasps, and other aculeate hymenopterans.
"Under the microscope, the bee's aculeus revealed the barbed tip that lodges in skin."
"The rose stem bore a slender aculeus at each node."
"Only female hymenopterans possess an aculeus, since it develops from the egg-laying apparatus."
The Latinate plural 'aculei' is standard in scientific writing; the anglicized 'aculeuses' also occurs but is less common.
"The specimen's aculei were clearly visible along the abdominal segments."
The word for a wasp's sting comes straight from Latin unchanged — Romans were swatting the same pests two thousand years ago.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of aculeus
Aculeus comes directly from Latin, where it meant a sting, prickle, or sharp point, ultimately related to the root acus, meaning needle. English adopted the word unaltered, primarily through scientific writing on plants and insects. It shares this 'sharp' root with acute, acumen, and acupuncture, all pointing back to the same idea of piercing precision.
Related word forms
How aculeus is actually used
A technical term found mainly in botany, zoology, and entomology rather than everyday speech; it retains its original Latin plural 'aculei' alongside the anglicized 'aculeuses'.
Easily confused with aculeus
Acuity means sharpness of mind or vision, while an aculeus is a literal physical sharp point such as a sting or prickle.
An acicula is a fine needle-like bristle or crystal, whereas an aculeus is a stinging point or prickle, especially on insects and plants.