1) Holdfast with a loop 2) Metal fastener 
• (n.) A bolt which a looped head, or an opening in the head.
A bolt having a head in the form of an open or closed anchor ring, or of a flattened and pierced section, with or without a collar or shoulder under the head.
Eye'bolt` noun (Machinery) A bolt with a looped head, or an opening in the head. 
a bolt having a ring-shaped head.