barnacle

¹ American  

[bahr-nuh-kuhl] / ˈbɑr nə kəl /

noun

1. any marine crustacean of the subclass Cirripedia, usually having a calcareous shell, being either stalked goose barnacle and attaching itself to ship bottoms and floating timber, or stalkless rock barnacle, or acorn barnacle and attaching itself to rocks, especially in the intertidal zone.

2. a person or thing that clings tenaciously.

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barnacle ² American  

[bahr-nuh-kuhl] / ˈbɑr nə kəl /

noun

1. Usually barnacles. an instrument with two hinged branches for pinching the nose of an unruly horse.

2. British Dialect. barnacles, spectacles.

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barnacle British  

/ ˈbɑːnəkəl /

noun

1. any of various marine crustaceans of the subclass Cirripedia that, as adults, live attached to rocks, ship bottoms, etc. They have feathery food-catching cirri protruding from a hard shell See acorn barnacle goose barnacle

2. a person or thing that is difficult to get rid of

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barnacle Scientific  

/ bär′nə-kəl /

1. Any of various small marine crustaceans of the subclass Cirripedia that form a hard shell in the adult stage and attach themselves to underwater surfaces, such as rocks, the bottoms of ships, and the skin of whales.

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Other Word Forms

• barnacled
  adjective

Etymology

Origin of barnacle¹

First recorded in 1580–85; perhaps a conflation of barnacle “barnacle goose” with Cornish brennyk, Irish báirneach “limpet,” Welsh brenig “limpets,” reflecting the folk belief that such geese, whose breeding grounds were unknown, were engendered from rotten ships' planking; see barnacle goose

Origin of barnacle²

1350–1400; Middle English bernacle bit, diminutive of bernac < Old French < ?

Explanation

A barnacle is a spineless animal that looks like a small circular white rock. You'll often find barnacles attached to the bottom of boats. Barnacles are crustaceans, which means they're related to crabs, lobsters, and shrimp, all of which have an external shell. In the case of barnacles, their shells attach to things like rocks, other shells, docks, and boats, and stay there permanently, filtering food from shallow ocean water through feathery appendages. The earliest use of the word referred to a European goose whose mythology described it hatching from the marine crustacean that eventually took its name.

Example Sentences

“We always joke that ever since then, EIT has been a barnacle on the side of the Meow Wolf ship, just hanging on but also occasionally hopping in to contribute,” Maier says.

From Los Angeles Times • May 20, 2026

A Ram truck with a yellow barnacle on its windshield, a handful of mopeds under rain covers, and a lot of empty parking spaces.

From Slate • Apr. 28, 2025

As these predators push out from the equator towards the poles, temperate prey species, like the barnacle Tetraclita rubescens, are encountering new, larger, predators.

From Science Daily • Nov. 9, 2023

“That’s what this group has done. They’ve given us the methods to decode the data that’s there—stored in barnacle shells.”

From National Geographic • Aug. 23, 2023

It was a tiny thing, perhaps the smallest barnacle in the world.

From "Charles and Emma: The Darwins' Leap of Faith" by Deborah Heiligman