1. Originally, an ornamental head band or fillet, worn by Eastern monarchs as a badge of royalty; hence (later), also, a crown, in general. The regal diadem.
2. Regal power; sovereignty; empire; considered as symbolized by the crown.
3. An arch rising from the rim of a crown (rarely also of a coronet), and uniting with others over its center. Diadem lemur.
4. (Science: zoology) The garden spider.
Origin: f. Diademe, L. Diadema, fr. Gr, fr. To bind round; through, across _ to bind; cf. Skr. Da to bind.