probable

Before probable meant “likely,” it belonged to the world of testing: Latin probāre meant to examine something and decide whether it passed muster. A Roman judge, inspector, or critic could therefore call something probabilis—not merely possible, but worthy of approval or belief. English picked up probable through Old French and Middle English in the late 14th century, while prove traveled along a related but slightly different route; the pair is a linguistic doublet, like two roads leaving the same Roman crossroads. Its relatives make the family even more revealing: probity is moral soundness, a probe is an instrument for testing, and a reprobate is someone judged unworthy. So when an idea is probable, imagine it standing before an ancient examiner—not certain, perhaps, but carrying enough evidence to pass the test.