"Sure-enough" means genuine, authentic, actual, or real. Its antonyms can be words like fake, phony, imaginary, or fictitious. "Sure-enough" can also mean confident, certain, or convinced, and antonyms can be words like doubtful, uncertain, or hesitant. Additionally, "sure-enough" can refer to something that is complete or thorough, and antonyms can be words like incomplete, unfinished, or inadequate. The use of antonyms is particularly helpful in language and vocabulary acquisition, because it allows speakers and writers to express opposing ideas and create a more diverse range of meanings.