Noun
center square (plural center squares) (American spelling)
A tool used to find the center of a circle, consisting of two perpendicular straight-edges, both placed tangent to the circular piece, and a third straight-edge which bisects the angle between the other two.
After a season of rotating center squares, former Hollywood Squares panelist Joan Rivers joined the series as the permanent center square. Source: Internet
After Goldberg's departure, the show decided not to employ a traditional permanent center square. Source: Internet
Shadoe Stevens was the announcer for the series and, beginning late in the first season, he also became a regular panelist occupying the bottom center square. Source: Internet
Eventually he assumed a permanent spot as the "center square," a move which ensured that he would be called upon by contestants at least once in almost every round. Source: Internet
If a piece falls into the center square, the game is over. Source: Internet
The three regulars also served as guest hosts for when Davidson was unavailable; in one of those instances, for one week at the beginning of the show's final season, Stevens hosted while Bullock was the center square and Howard Stern announced. Source: Internet