The word "ittybitty" is an informal slang term that refers to something very small. Its antonyms are words that express the opposite meaning. The antonyms for "ittybitty" are significant, substantial, considerable, sizable, generous, ample, substantial, and extensive. These words convey a sense of largeness or abundance, rather than smallness. To use them in a sentence, one might say, "The garden was not ittybitty, but rather extensive and lush with plants of all sizes." It is important to use the appropriate antonym for the context to convey the intended message accurately.