hold·fast /ˈhol(d)ˌfæst/
  可夾緊之用物
  Hold·fast 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. “His holdfast was gone.”
  2. Bot. 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.
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  holdfast
       n : restraint that attaches to something or holds something in
           place [syn: fastener, fastening, fixing]