A very large public investment project, especially one costing more than one billion US dollars(noun)
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Use "megaproject" in a sentence
"We need an integrated rapid transit web to serve the region and planning it piecemeal, or as after-thoughts or after-market add-ons after each new megaproject is built, won't get us to there."
"And although three tracks made their way to the Internet early two on purpose, the album is the first major-label megaproject in years that didn't leak in its entirety ahead of time."
"Seattle monorail is an example of the kind of megaproject fiasco local politicians rush to embrace, and nothing suggests they've learned any substantive lessons from it."