The action or event of a space having more occupants than that space can accommodate.(noun)
Present participle of overcrowd.(verb)
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Use "overcrowding" in a sentence
"At best the term overcrowding is a relative one, and the scale of official measurement conveniently sliding."
"The care centers for addicts have increased, as has criminal behaviour related to the use of approved and non approved drugs resulting in overcrowding of jails, mental health problems, and physical health problems."
"According to viewers, Kifowit lectured everyone last night on when the Hometown project was originally proposed, it promised not to result in overcrowding, large increases of students, traffic and parking problems, but all of those happened with deteriorating quality of life."