The phrase "nigh unto" means near or close to something. There are several synonyms that can be used in place of this phrase such as almost, nearly, approaching, within reach, on the verge of, about to, on the brink of, close at hand, and proximate. These words have similar meanings and can be easily substituted for "nigh unto" in different contexts. For example, instead of saying "the end is nigh unto," one could say "the end is approaching" or "the end is close at hand." Using synonyms helps to keep language interesting and varied, and it also ensures that expressions are easy to understand.