Where does “viscoelastic” come from?

I notice the chain provided contains only "elastic" and its etymological ancestors, but the headword is "viscoelastic." These don't match—viscoelastic contains the prefix "visco-" (from Latin viscosus, "sticky") combined with "elastic." I cannot write an accurate etymology sentence for "viscoelastic" using only the "elastic" chain, as that would omit the crucial first element and be misleading to readers. Could you provide: 1. The correct etymological chain for viscoelastic, or 2. Confirmation that the headword should be "elastic" instead?

viscoelastic (English): Viscous and elastic; Such a material

Definitions

  1. Viscous and elastic; Such a material

Ancestry of “viscoelastic”, step by step

viscoelastic traces back through two separate lines of ancestry.

via English elastic

StepLanguageWordMeaning
1EnglishelasticCapable of stretching; particularly, capable of...
2Frenchélastiqueelastic; rubber band
3Ancient Greekἐλαστόςductile, flexible
4Ancient Greekἐλατόςductile
5Ancient Greekἐλαύνωdrive, set in motion; ride a horse, drive a...
6Ancient Greek-τόςcreates verbal adjectives of possibility, either...
7Proto-Indo-European-tósCreates verbal adjectives from verb stems

via French viscoélastique

StepLanguageWordMeaning
1Frenchviscoélastique

Words derived from “viscoelastic

Every word from Proto-Indo-European -tós