What does cerci mean?
Cerci are a pair of jointed appendages found at the posterior end of the abdomen in many insects and certain other arthropods. Though small, they play an important role as sensory organs, detecting touch, vibration, and subtle movements of air or water — which is how a cockroach, for example, can sense an approaching threat from behind and scurry out of reach. In some groups, such as earwigs, cerci have been modified into distinctive pincer-like structures used for defence, prey capture, or folding wings. The word is the plural form of "cercus," derived from the Greek "kerkos," meaning tail. Strictly a technical zoological term, "cerci" appears mainly in entomological literature rather than everyday speech, but it offers a precise way to describe structures that laypeople might loosely call an insect's 'tail' or 'pincers.'
nounCerci are a pair of small, jointed appendages at the rear end of the abdomen of many insects and other arthropods, serving as sensory organs that detect touch, vibration, and air currents.
- The pair of jointed sensory appendages projecting from the last abdominal segment of many insects and other arthropods.
"The entomologist noted that the earwig's forceps-like cerci were unusually long for its body size."
"Cockroaches use their sensitive cerci to detect approaching predators from behind."
"In mayflies, the long thread-like cerci extend well beyond the tip of the abdomen."
"Cerci" is itself the plural form; the singular is "cercus."
"Each cercus bears several fine sensory hairs."
An earwig's 'pincers' aren't pincers at all — they're actually modified cerci.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of cerci
The word "cerci" is the plural of "cercus," borrowed into scientific Latin usage from the ancient Greek "kerkos" (κέρκος), meaning "tail." The term entered English through zoological nomenclature, likely in the nineteenth century as comparative anatomy and entomology formalised their descriptive vocabulary. It shares its Greek root with related scientific terms built on the same stem, all referring to tail-like structures.
Related word forms
How cerci is actually used
"Cerci" is a technical term used almost exclusively in entomology and zoology; it is the plural of "cercus" and should be treated as such in formal scientific writing.
Easily confused with cerci
A cervix is the narrow lower part of the uterus, whereas cerci are paired sensory appendages at the tip of an insect's abdomen.