FID, noun 1. A square bar of wood or iron, with a shoulder at one end, used to support the top-mast, when erected at the head of the lower mast. 2. A pin of hard wood or iron, tapering to a point, used to open the strands of a rope in splicing.
Source: Webster's 1828 American Dictionary ↗ · public-domain · returned verbatim, no AI