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.
philosophers have speculated on the question of God for thousands of years
spectrograph
spectrometer
spectroscope
spectrum
specular
speculate
speculation
speculative
speculator
speculum
sped
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