Chūdan (中段) is one of the three heights commonly referred to in Japanese martial arts. It roughly means `middle level`, and refers to the space above and including the waist, and below but not including the shoulders. The most common strikes to the chūdan area target either the solar plexus or floating ribs. ... Found on http://en.wikipedia.org/wiki/Chūdan
Mid-section. During the practice of KIHON IPPON KUMITE (one step basic sparring), the attacker will normally announce where he/she will attack JODAN, CHUDAN, or GEDAN (Upper level, Mid-level, or lower level). Found on http://www.jkra.com/karate_glossary.htm