pileup

UK: /ˈpaɪlʌp/ US: /ˈpaɪlˌʌp/ ,(pīl′up′)

WordReference Random House Learner's Dictionary of American English © 2025

pile•up /ˈpaɪlˌʌp/   n. [countable]

1. a collision of several moving vehicles:
   a bad pileup on Interstate 80.
2. an accumulation, as of chores or bills.

WordReference Random House Unabridged Dictionary of American English © 2025

pile•up  (pīl′up′), n. 

1. a massive collision of several or many moving vehicles.
2. an accumulation, as of work, chores, or bills.
3. a rough or disorderly falling of people upon one another, as in a football game.

• noun, nominal use of verb, verbal phrase pile up 1825–35

Collins Concise English Dictionary © HarperCollins Publishers::

pile up verb (adverb)

1. to gather or be gathered in a pile; accumulate
2. to crash or cause to crash

noun pile-up

1. a multiple collision of vehicles