Merriam-Webster Collegiate Dictionary - theater

 I. noun  or theatre  Etymology: Middle English theatre, from Middle French, from Latin theatrum, from Greek theatron, from theasthai to view, from thea act of seeing; akin to Greek thauma miracle  Date: 14th century  1.  a. an outdoor structure for dramatic performances or spectacles in ancient Greece and Rome  b. a building or area for dramatic performances  c. a building or area for showing motion pictures  2. a place or sphere of enactment of usually significant events or action the ~ of public life  3.  a. a place rising by steps or gradations a woody ~ of stateliest view — John Milton  b. a room often with rising tiers of seats for assemblies (as for lectures or surgical demonstrations)  4.  a. dramatic literature ; plays  b. dramatic representation as an art or profession ; drama  5.  a. dramatic or theatrical quality or effectiveness  b. spectacle 1a  c. entertainment in the form of a dramatic or diverting situation or series of events t public feud made for good ~  6. ~ of operations  II. adjective  Date: 1977 of, relating to, or appropriate for use in a ~ of operations ~ nuclear weapons