The term "v'tosh ka'tur" referred to "Vulcans without logic." In Vulcan, it was used by elders to refer to anyone who disagreed with ancestral teachings. Around 2143, a group of these Vulcans left their homeworld aboard the starship Vahklas. The crew of Enterprise NX-01 encountered the Vahklas' 'in 2151 while on route to the Arachnid Nebula. Their ship's captain, Tavin, requested some assistance in the repair of their propulsion and life support.
In truth, these Vulcans hadn't abandoned their logic but simply learned to exist without the need to continually repress their emotions. They still believed "logic" was an essential part of Vulcan existence. But that it had to complement "emotions", not exclude them. After 8 years of experimentation, they claimed to have finally managed to find a balance between the two through constant discipline and meditation. (ENT: "Fusion", "Stigma")
Sybok presumably would be considered a "v'tosh ka'tur" as well.