- the act of holding fast
- any of various devices that hold something else in place; hook, nail, clamp, etc.
- Bot. a part of certain rootless plants, as some algae, used to attach the plant to a surface
- Zool. an organ of a parasitic or sessile organism, specialized for attachment to a host or other object
- Any of various devices used to fasten something securely.
- Biology An organ or structure of attachment, especially the basal, rootlike formation by which certain seaweeds or other algae are attached to a substrate.