holdfast

noun

hold·​fast ˈhōl(d)-ˌfast 

plural holdfasts

1

: something to which something else may be firmly secured

Fire damage has revealed metal holdfasts used to attach … to the brickwork …

—Harriet Sherwood

(figurative) But leaders also need personal moorings and holdfasts that help guide tough choices and the consequences that ensue.

—Chad Blair

2

a

: a rootlike part by which a usually aquatic organism (such as an alga or sponge) clings to a substrate

During storms—and occasionally when sea urchins eat through a holdfast—whole kelp plants can become detached, rising to the surface where they form free-floating rafts.

—Alistair Hobday

… an external network of holdfasts that anchor the individual mussel to the substrate.

—Douglas Smith

Clinging vines can attach themselves to flat surfaces using aerial roots growing from their stems or special structures called holdfasts.

—Dan Gill

b

: an organ by which a parasitic animal (such as a tapeworm) attaches itself to its host

After parasitic worms reach their final habitats, there must be some mechanism to keep them there. … The most effective and economical method to resist these flows is to use an attachment organ or holdfast.

—Michael V. K. Sukhdeo

Examples of holdfast in a Sentence

Recent Examples on the Web

Species with aerial roots or root-like holdfasts include trumpet vine (Campsis radicans), poison ivy, and climbing hydrangeas (Climbing Hydrangea, Hydrangea anomala petiolaris, Japanese hydrangeavine, Schizophragma hydrangeoides, and woodvamp, Decumaria barbara). —Miri Talabac, Baltimore Sun, 14 Nov. 2024

These underwater forests, made of large brown algae, thrive off the coast, anchored to rocky reefs with their unique holdfast roots. —David L. Coddon, San Diego Union-Tribune, 18 Apr. 2024

Then her beauty acted like a mooring for her other outward qualities, undulating from that holdfast like fronds of kelp on the sea. —Jeff Wheelwright, Discover Magazine, 20 May 2012

Trilobites would scuttle across the ocean floor past primitive sea anemones gripping the bottom with their fleshy holdfasts. —Michael Greshko, National Geographic, 21 Mar. 2019

State rules required cutters to trim above the lowest branches and no closer than 40 centimeters from the holdfast—the sturdy foot with which rockweed grips the shore—to allow the plants to regrow after each haircut. —Ben Goldfarb, Smithsonian, 31 May 2018

The vine also produces holdfasts, and is consequently an excellent tree climber, growing aggressively upward, eventually strangling its host. —Dave Taft, New York Times, 20 Jan. 2017

Word History

First Known Use

1566, in the meaning defined at sense 1

Kids Definition

holdfast

noun

hold·​fast ˈhōl(d)-ˌfast 

: a part by which a plant (as a seaweed) or animal (as a tapeworm) clings (as to a flat surface or the body of a host)

Medical Definition

holdfast

noun

hold·​fast ˈhōl(d)-ˌfast 

: an organ by which a parasitic animal (as a tapeworm) attaches itself to its host