holdfast

UK: /ˈhəʊldˌfɑːst/ US: (hōld′fast′, -fäst′)

WordReference Random House Unabridged Dictionary of American English © 2025

hold•fast  (hōld′fast′, -fäst′), n. 

1. something used to hold or secure a thing in place;
   a catch, hook, clamp, etc.
2. Botany, Fungi any of several rootlike or suckerlike organs or parts serving for attachment.

• noun, nominal use of verb, verbal phrase hold fast 1550–60

Collins Concise English Dictionary © HarperCollins Publishers::

holdfast / ˈhəʊldˌfɑːst/ noun

1. the act of gripping strongly
2. any device used to secure an object, such as a hook, clamp, etc
3. the organ of attachment of a seaweed or related plant