theatre-in-the-round

noun plural theatres-in-the-round

a theatre with seats arranged around a central acting area
drama written or designed for performance in such a theatre

Also called: arena theatre
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012