cocksure

/ˈkäk-ˈshu̇r/

probably from + sure

adjective

  1. feeling perfect assurance sometimes on inadequate grounds

  2. marked by overconfidence or presumptuousness : cocky

sure certain positive cocksure mean having no doubt or uncertainty. sure usually stresses the subjective or intuitive feeling of assurance. certain may apply to a basing of a conclusion or conviction on definite grounds or indubitable evidence.