setae

setae — noun

1. thin, stiff, hair-like growths on the bodies of some animals and plants, helping

1.nounC2
Definition

thin, stiff, hair-like growths on the bodies of some animals and plants, helping them grip surfaces, sense their surroundings, or defend themselves

Example

Nora watched the earthworm use tiny setae along its body to grip the soil.

setae grip surfaces to aid movement

The caterpillar's setae left a red, itchy rash on Amir's arm after he touched it.

setae can cause skin irritation on contact

Common collocations
  • tiny setae
  • fine setae
  • stiff setae
  • covered with setae
  • rows of setae
Synonyms
  • bristles

    a broader, everyday term for any short stiff hair; 'setae' is the precise biological term

  • hairs

    too general — most hairs are soft and flexible, while setae are specifically stiff and often serve a mechanical function

Usage Note

Setae is the plural form; one individual bristle is called a seta. This term appears almost exclusively in scientific contexts, especially zoology and botany.

Common Mistakes

I found a setae on the leaf.
I found a seta on the leaf.
'setae' is the plural form; use 'seta' for a single bristle.

Word family

  • seta
    nounC2

Synonym discussion

Sense: noun/1

Setae, bristles, hairs, spines, and cilia all describe small projecting structures on organisms, but they differ in biological precision and context. Bristles are the closest everyday term — a brush has bristles, and so does a boar — but 'setae' is the formal zoological label reserved for the stiff, often movable hair-like organs found on annelids, arthropods, and some plants. Hairs are finer, softer, and typically serve insulation in mammals, not locomotion or defence. Spines are thicker, sharper, and usually fixed in place for protection (like those of a hedgehog or cactus). Cilia are microscopic, hair-like organelles that beat in coordinated waves to move fluid or single cells — far smaller and more specialised than setae. If you see a biologist describing 'setae' on an earthworm, picture tiny gripping bristles, not fur or fuzz.

bristles ↗hairs ↗spines ↗cilia

Etymology

LatinEnglish

From Latin seta (also spelled saeta), meaning 'a stiff hair' or 'bristle.' The word entered English in the 18th century as a technical term in natural history and remains firmly within scientific usage. The plural form setae follows the regular Latin plural pattern for first-declension feminine nouns.

First known use

1793

1793, in the meaning defined above