Speculate

google

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late 16th century: from Latin speculat- ‘observed from a vantage point’, from the verb speculari, from specula ‘watchtower’, from specere ‘to look’.

wiktionary

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Borrowed from Latin speculātus, past participle of speculor(“look out”), from specula(“watchtower”), from speciō(“look at”)

etymonline

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speculate (v.)

1590s, "view mentally, contemplate" (transitive), back-formation from speculation. Also formerly "view as from a watchtower" (1610s). Intransitive sense of "pursue truth by conjecture or thinking" is from 1670s. Meaning "to invest money upon risk for the sake of profit" is from 1785. Related: Speculated; speculating.