In boxing, a cross is a counter-punch. The cross is a power-punch like the uppercut and hook. Compubox, a computerized punch scoring system, counts the cross as a power-punch.
A good definition is a punch usually thrown with the right hand (a right cross) the instant an opponent leads with his left. The blow crosses over the leading arm.
Boxing, however, probably grew most specifically out of the demonstrations held at the fives court and the tennis court in London in the early 19th century.
In the late 19th and early 20th century, amateur boxing was encouraged in schools, universities and in the armed forces, but the champions, in the main, came from among the urban poor.
Boxing in the 1930s, despite being hit by depression, saw one of the greatest boxers of all time: Joe Louis.