The Collaborative International Dictionary
Gorgoneion \Gor`go*ne"ion\ (g[^o]r`g[-o]*n[=e]"y[o^]n), n.; pl.
Gorgoneia. [NL., fr. Gr. Gorgo`neios, equiv. to Gorgei^os
belonging to a Gorgon.] (Arch.)
A mask carved in imitation of a Gorgon's head.
--Elmes.
Wiktionary
n. (context architecture English) A mask carved in imitation of a gorgon's head.
Wikipedia
In Ancient Greece, the Gorgoneion ( Greek: Γοργόνειον) was a special apotropaic amulet showing the Gorgon head, used most famously by the Olympian deities Athena and Zeus: both are said to have worn the gorgoneion as a protective pendant. It was assumed, among other godlike attributes, as a royal aegis to imply divine birth or protection, by rulers of the Hellenistic age, as shown, for instance, on the Alexander Mosaic and the Gonzaga Cameo.
Usage examples of "gorgoneion".
The shield has a boss, a Gorgoneion, a picture of Gorgo the Medusa, who could turn those who looked at her to stone.