Ushiro Geri Chudan is a technique in Kyokushin karate. It translates to 'Rear Kick to the Midsection.' This technique involves executing a kick with the rear leg to target the opponent's midsection or torso from behind. The term 'Ushiro' refers to the rear, 'Geri' indicates the kick, and 'Chudan' specifies the midsection. It is commonly used to strike the opponent's abdomen or ribs with significant force.