1. not able to be decided or determined; impossible to resolve definitively
2. relating to a mathematical or logical problem that cannot be solved by any algorithm
Usage: mathematics; computer science

Examples

• The dispute between the neighbors seemed undecidable without more evidence.
• Some philosophical questions may be fundamentally undecidable.
• The halting problem is a famous undecidable problem in computer science.
• The committee found the case undecidable based on the conflicting testimony.
• Certain mathematical propositions are undecidable within formal systems.
• The question of which candidate was better remained undecidable after the debate.