Synonyms for the word "ungroundable" would include phrases like "beyond reproach", "unassailable" or "unimpeachable". These terms describe a situation where there is absolutely no viable reason or valid argument to find fault or blame someone. Another viable synonym for "ungroundable" could be "irrefutable", which means that any dispute or challenge to a position or decision would be impossible to convincingly oppose. Additionally, phrases like "unfathomable" or "beyond dispute" can also convey the same meaning, emphasizing the impossibility of finding any valid reason to disagree or criticize. Synonyms for "ungroundable" provide various options to express an idea that is unequivocal and steadfast in its position.