velarium

plural velaria · plural velariums

1. biologyThe marginal membrane of certain medusae belonging to the Discophora.
2. historicalAn awning that stretched over the seating area of the Colosseum in Ancient Rome and other Roman amphitheaters.
3. A cloth stretched over another space, such as that stretched below the roof of the Royal Albert Hall.

   In accordance with the epochal significance of the occasion, Berlin was decked out as never before in its history. […] A velarium suspended over Unter den Linden depicted the great military victories that had finally brought Germany its unity.

   2007 October 15, David Clay Large, Berlin, Basic Books, →ISBN

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   Royal Albert Hall [was dedicated] by the Prince of Wales (later King Edward VII). As The Times reported on the next day: 'The address [...] was somewhat marred by an echo [...]'. To Col. Scott, the designer of the huge roof structure, this acoustic problem was a mere irritant which could be solved by a velarium of cloth (weighing 1+¹⁄₄ tons) stretched underneath the roof. But in spite of experiments with the height of the velarium, the echo persisted […]

   2009 September 28, Michael Barron, Auditorium Acoustics and Architectural Design, Routledge, →ISBN, page 134