holdfast

Everyday

1. (science) The root-like part at the bottom of seaweed that holds it tightly to rocks. tree →
2. A clamp or hook that holds something firmly, for example to a workbench or wall. tree →
3. (old) Something you can hold on to firmly. tree →

In the lessons

In science lessons on the seashore and kelp forests, the holdfast is not a real root: it only grips the rock and does not take in food. In woodwork, a holdfast clamps wood to the bench. Phrases: a kelp holdfast, a seaweed's holdfast.

Examples

• The seaweed's holdfast stuck tightly to the rock. tree →
• A holdfast is not a root, because it does not take in water. tree →
• Storms can tear kelp from its holdfast. tree →
• The carpenter used a holdfast to clamp the wood to the bench. tree →
• Tiny crabs hide inside kelp holdfasts. tree →

Note

One word: hold + fast («fast» here means firmly, as in «stuck fast»). Plural: holdfasts. A science and craft word, rarely used in everyday talk.