Holdfast /(?)/

Hold·fast

Holdfast

n.
  1. Something used to secure and hold in place something else, as a long flat-headed nail, a catch a hook, a clinch, a clamp, etc.; hence, a support.
  2. A conical or branching body, by which a seaweed is attached to its support, and differing from a root in that it is not specially absorbent of moisture. (Bot.)