For the root-like plant structure that anchors seaweed, see holdfast

A hold fast being used to affix a board to the benchtop for chiseling dovetails

A hold fast is an accessory used on a woodworking workbench to fix a workpiece to the top or side of the bench while it is being worked. Plants are living Organisms belonging to the kingdom Plantae. Seaweed is a loose colloquial term encompassing macroscopic Multicellular, benthic marine Algae. A holdfast is a Root -like structure that anchors aquatic Sessile organisms such as Seaweed, other sessile Algae, stalked A Workbench is a table used by woodworkers to hold workpieces while they are worked by other tools

A hold fast is shaped like a shepherd's hook. In use, the shank fits into a hole in the top or side of the bench and the tip of the hook is pressed against the work. The hold fast is set by rapping the top with a mallet and is released by hitting the back side. A good holdfast works remarkably well, and is inexpensive and easy to install.

A holdfast is also a plinth or pedestal, usually of concrete, to which an anti aircraft or coastal battery gun was fitted. Holdfasts are often the only evidence for a weapon which survive.

To ‘hold fast’ – military or nautical term meaning to stand where you are ‘Hold fast’ – showing courage