Where does “ἱστορικός” come from?

ἱστορικός (Ancient Greek) comes from Ancient Greek ῐ̔στορῐ́ᾱ, from Ancient Greek ῐ̔στορέω, from Ancient Greek ἵστωρ, from Proto-Hellenic wístōr, from Proto-Indo-European wéydtōr, from Indo-European *weyd-.

ἱστορικός (Ancient Greek): exact, precise, scientific; belonging or...