Today it means: A former county of Nye, Nevada, United States, containing Yucca Mountain; but having no residents, no buildings, no roads; except for the infrastructure of the U.S. national nuclear waste storage site at Yucca. Bullfrog county, a 12mix12mi square centered around Yucca, was split from Nye County in 1987 and merged back into it in 1989. The county of Bullfrog was completely enclaved inside Nye. The county seat was Carson City, the capital of Nevada, and not located inside Bullfrog. Full definition →
bullfrog + county. The county is named after the former mining district of Bullfrog, which was named after the Bullfrog Mining Company, which was named after the Bullfrog Mine, which was named after the color of the gold ore the mine, colored like a bullfrog, which in turn refers the frog.
Etymology from Wiktionary, CC BY-SA 4.0.