__ Boy, Atomic Superhero Sidekick in the Simpsons
Puzzle 8 of Under the Ground Easy Pack
Question is: __ Boy, Atomic Superhero Sidekick in the Simpsons
and the answer is: FALLOUT
Word Meaning:
FALLOUT — The event of small airborne particles falling to the ground in significant quantities as a result of major industrial activity, volcano eruption, sandstorm, nuclear explosion, etc.
Definitions from Wiktionary.