Definition of "pile up" [pile up]

• To form a pile, stack, or heap. (verb)
• To collect or accumulate, as a backlog. (verb)

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• "My wife, the journalist Jean Marbella, who rolls her eyes when the books on arcane subjects begin to pile up in the bedroom and announce the arrival of a new Swagger adventure, but hangs in through it all."
• "The trailer had been used as an office for the business, but Uncle Jake had let the secretary go and let the bills pile up on the beat-up wooden desk that sat in the living room area."
• "The worst-hit section of the highway is in between Kangpokpi to Mao town (65 km), as the villagers pile up stones upto 4/5 feet along the route, besides felling trees and making large trenches."