The term 'excessively theatrical' can be summed up by the word 'STAGY', which is defined as 'overly theatrical or melodramatic'. This term is often used to describe a performance that is overly dramatic and exaggerated, with an emphasis on grand gestures and over-the-top emotions. It is often seen in performances of classical plays, musicals, and operas, where the actors are expected to put on a showy display of emotion and movement.