Where does “downblend” come from?

downblend (English) comes from English Down, from Middle English doun, from Old English dūn, from Proto-Germanic *dūnā, from Proto-Celtic dūnom, from Proto-Indo-European dʰewh₂- — smoke; mist, haze.

downblend (English): To blend highly-enriched uranium, typically from decommissioned nuclear weapons, with uranium containing a low concentration of fissile uranium-235 (slightly-enriched uranium, natural uranium, or depleted uranium) in order to convert it to low-enriched uranium suitable for use as fuel in standard po

Definitions

To blend highly-enriched uranium, typically from decommissioned nuclear weapons, with uranium containing a low concentration of fissile uranium-235 (slightly-enriched uranium, natural uranium, or depleted uranium) in order to convert it to low-enriched uranium suitable for use as fuel in standard po

Ancestry of “downblend”, step by step

downblend traces back through two separate lines of ancestry.

via English Down

Step	Language	Word	Meaning
1	English	Down	usually known as County Down
2	Middle English	doun	down
3	Old English	dūn	hill, down; hill, dune; hill, mountain
4	Proto-Germanic	*dūnā	—
5	Proto-Celtic	dūnom	stronghold, rampart
6	Proto-Indo-European	dʰewh₂-	smoke; mist, haze

via English blend

Step	Language	Word	Meaning
1	English	blend	A mixture of two or more things; A word formed by...
2	Middle English	blenden	—
3	Old Norse	blanda	to blend, mix
4	Proto-Germanic	blandaną	to blend, make murky; to mix, mingle
5	Proto-Indo-European	bʰlendʰ-	to blend, to mix up; to make cloudy, opaque;...

Every word from Proto-Indo-European dʰewh₂- →Every word from Proto-Celtic dūnom →Every word from Proto-Germanic *dūnā →