Someone who makes conjectures or guesses.
El conjeturador propuso varias teorías sobre el origen de la vida, aunque muchas eran difíciles de probar.
The conjecturer proposed several theories about the origin of life, although many were difficult to prove.
El conjeturador formuló varias hipótesis sobre el futuro de la economía.
The conjecturer formulated several hypotheses about the future of the economy.