noun pl. fibulae -·lae′ (-lē′) or fibulas -·las

1. the long, thin outer bone of the human leg between the knee and the ankle
2. a similar bone in the hind leg of other animals
3. in ancient Greece or Rome, a buckle or clasp for fastening garments

Etymology: L, a clasp, pin (< base of figere, to fasten, fix): the bone, as it appears in man, is like a clasp