"Taikyoku" means "first cause". This is the first in a classic series of katas that originated with Funakoshi Gichin Sensei's Shotokan style.
"Gichin "Shoto" Funakoshi Sensei named the set of three Taikyoku kata developed by his son Yoshitaka “Gigō” Funakoshi Sensei. In his book "Karate-do Kyohan" Funakoshi, he explains the development of the kata and why he named them Taikyoku, which translates as First Cause.
"He also wrote: “Because of its simplicity, the kata is easily learned by beginners. Nevertheless, as its name implies, this form is of the most profound character and one to which, upon mastery of the art of karate, an expert will return to select it as the ultimate training kata” (page 42, ‘Karate-Do Kyohan’). (a side note:- The Chinese kanji used for the name Taikyoku (太極) are pronounced as "Tai Chi" in Chinese, which translated as "Grand Ultimate")."