Velarium

·noun The marginal membrane of certain medusae belonging to the Discophora.

velarium
vēlārĭum, ii, n. [velum], a covering , screen , awning , stretched above the theatre to keep off t...

A New Latin Dictionary by Charlton T. Lewis Ph.D. and Charles Short, LL. D.
velarium
vēlārium ī, n velum.—In a theatre, an awning, screen (to protect spectators from the sun), Iu. ...

An Elementary Latin Dictionary