'conjectural' originates from Latin, specifically the word 'conjecturalis,' where 'con-' meant 'together' and 'jacere' meant 'to throw.'

'conjecturalis' transformed into the French word 'conjectural,' and eventually became the modern English word 'conjectural' through Middle English.

Initially, it meant 'to throw together ideas or guesses,' but over time it evolved into its current meaning of 'based on conjecture or speculation.'