Gedan Tettsui Yoko Uchi is a technique in Kyokushin karate. It translates to 'Low-Level Hammer Fist Side Strike.' This technique involves delivering a powerful strike with the hammer fist to the opponent's side at a low level. The term 'Gedan' refers to the low level, 'Tettsui' indicates the hammer fist, and 'Yoko Uchi' refers to the side strike. It is effective for targeting the lower ribs or midsection with significant force.