Plural of conjecture: multiple guesses or inferences; or third-person singular present of conjecture, meaning to guess or infer.
Conjecture itself comes from Latin coniectura. The third-person singular -s in English developed from Old English verb endings and is now the standard present-tense marker.
Goldbach's Conjecture, one of math's greatest unsolved mysteries, started as a simple letter between two mathematicians in 1742—showing how a single conjecture can occupy humanity for centuries.
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