Definition from Wiktionary, the free dictionary
holdfast (plural holdfasts)
- Something to or by which an object can be securely fastened.
- (zoology) A root-like structure that anchors aquatic sessile organisms, such as seaweed, other sessile algae, stalked crinoids, benthic cnidarians, and sponges, to the substrate.
- (archaic, medicine) Actinomycosis.