Where does “放射性降下物” come from?

放射性降下物 (Japanese) comes from Japanese 放射性, from Japanese 放射, from English radiation, from Latin radiatio, from Latin -tiō, from Latin dissertātiō, from Latin dissertus, from Latin disserere — small stone, pebble; gravel, rubble.

放射性降下物 (Japanese): nuclear fallout

Definitions

nuclear fallout

Ancestry of “放射性降下物”, step by step

放射性降下物 traces back through 3 separate lines of ancestry.

via Japanese 放射性

Step	Language	Word	Meaning
1	Japanese	放射性	radioactivity
2	Japanese	放射	radiation; emission; emit, radiate
3	English	radiation	The shooting forth of anything from a point or...
4	Latin	radiatio	glittering, shining, radiation
5	Latin	-tiō	tion, -ation, -ing
6	Latin	dissertātiō	(spoken) dissertation, discourse, disquisition
7	Latin	dissertus	arranged, disposed; explained
8	Latin	disserere	second-person singular future passive indicative...
9	Latin	dis-	asunder, apart, in two; reversal, removal;...
10	Latin	calceus	shoe
11	Latin	calx	limestone; chalk; the finish line
12	Ancient Greek	χάλιξ	small stone, pebble; gravel, rubble

via Japanese 物

Step	Language	Word	Meaning
1	Japanese	物	thing; story, genre
2	Japanese	物言い	a way of speaking, wording
3	Japanese	物言う	to talk

via Japanese 降下

Step	Language	Word	Meaning
1	Japanese	降下	descent

Every word from Ancient Greek χάλιξ →Every word from Latin -tiō →Every word from Latin dis- →