In boxing, a chin refers to a boxer's ability to tolerate punishment in the face without being knocked out. A boxer with a "good chin" refers to a boxer with tremendous ability to absorb punishment in the face, which can also be called "having a beard", "Iron chin", or "good whiskers". Boxers noted to have good chins are Muhammad Ali, Joe Frazier, Rocky Marciano, Jake LaMotta, Tex Cobb, Carmen Basilio, Marvin Hagler, José Luis Castillo, Evander Holyfield, David Tua, James Toney, George Chuvalo and others. There is a dispute as to the physiology of having a "good chin." Some believe that a strong neck that resists a sudden angular acceleration of the head is what makes a "good chin." Supporters of this belief point to Evander Holyfield and Marvin Hagler, both of whom were strong and had large trapezius muscles around the neck. Other believe that a having a "chin" is a product of one's determination. A boxer with a "bad chin", or "glass chin", refers to boxers with limited ability to absorb punishment in the face. Many clubfighters and journeymen may have glass chins, although it may depend on weight class or sometimes legs. Wladimir Klitschko is sometimes referred as having a glass chin, although some boxing experts, such as Teddy Atlas, believe it to be a mindframe. Lennox Lewis is also criticized for having a glass chin, having been knocked out by people not known for being punchers, this is also disputed as he absorbed punishment from notorious power puncher David Tua.
