Polymeros (πολυμερής) means 'in many parts' or 'at many times' — from poly (many) + meros (part/portion). It appears only in Hebrews 1:1 in the magnificent opening: 'In the past God spoke to our ancestors through the prophets at many times and in various ways (polymeros kai polytropos).' This adverb captures the progressive, partial, multi-staged nature of Old Testament revelation — each piece a genuine word of God, but none the whole picture.
Hebrews 1:1–2 creates a deliberate contrast: God spoke polymeros (in many parts) through the prophets — but 'in these last days he has spoken to us by his Son.' The many-parted speech of the Old Testament (law, psalms, prophecy, wisdom) was real revelation, but fragmentary. Jesus is the full and final Word — not a new installment but the whole message gathered into one Person. Progressive revelation culminates not in a book but in a Person.
Polymeros opens the greatest theological argument in Scripture: the superiority of Christ. But it does so by honoring what came before. The prophets spoke truly and from God — but partially. The Law was genuine revelation — but preparatory. Each piece was a meros (part) of a whole that only Christ fully embodies. This is why Christians do not discard the Old Testament but read it as the build-up to the One who is all its parts made whole.