Past tense of probe: to investigate or examine something carefully, or to poke into something with a thin instrument.
From Late Latin 'proba' (proof, test). The medical meaning (using a thin instrument to examine a wound) came first in the 1600s, and the figurative meaning (to investigate) evolved from that, since both involve getting beneath the surface.
The word 'probe' was first used for medical instruments, but then NASA named its spacecraft probes the same thing because they're designed to 'probe' into space exactly like a doctor probes into wounds!
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