Definition of holdfasts:
(n) :
Something to or by which an object can be securely fastened.
(n) :
(biology) A root-like structure that anchors aquatic sessile organisms, such as seaweed, other sessile algae, stalked crinoids, benthic cnidarians, and sponges, to the substrate.
(n) :
The aspect of a character that experiences destructive temptation.
(n) :
(archaic, medicine) Actinomycosis.
(n) :
A hamlet and civil parish (served by Longdon, Queenhill and Holdfast Parish Council) in Malvern Hills district, Worcestershire, England (OS grid ref SO853378).