Indistinguishableness is a word used to describe the inability to distinguish or differentiate between two or more things. Synonyms for this word include similarity, resemblance, identicalness, sameness, and likeness. These words express the idea that two or more things are so similar that it is difficult or impossible to tell them apart. Other synonyms include uniformity, consistency, and congruity. These words suggest that there is a harmony or agreement between the things being compared. Additionally, terms like homogeneity, parity, and equivalence convey the idea of equal or identical qualities between the things being compared. In summary, there are several synonyms for indistinguishableness that can be used to describe the similarity and equality between two or more things.