Conjecture
Foundations and logic
A precisely stated mathematical claim that is expected to be true but has neither been proved nor disproved.
What is usually left out
The word carries no guarantee. Conjectures are regularly disproved, sometimes after enormous amounts of supporting evidence: Polya’s conjecture survived checks up to hundreds of millions before a counterexample was found. A conjecture is a question with an opinion attached, not a weaker kind of theorem.