The phrase "without number" refers to an infinite or uncountable amount of something. When it comes to synonyms for this phrase, there are a few options to choose from depending on the context. One possibility is "countless," which means too many to be counted or enumerated. Another option is "innumerable," indicating a number that is impossible to calculate or measure. "Limitless" is another choice, referring to something that has no bounds or restrictions. Finally, "boundless" can also be used to describe a limitless or immeasurable quantity. Regardless of the word chosen, they all convey the idea of a vast and unquantifiable amount.