Every seat is occupied; fully packed, indicating great popularity.
虚空。座位没有空着的。形容出席的人很多。
《晋书·王浑传》时吴人新附，颇怀畏惧。浑抚循羁旅，虚怀绥纳，座无空席，门不停宾，于是江东之士莫不悦附。”
The theater was packed, with no empty seats at all.
Learn the next connected idiom: 座无虚席 (zuò wú xū xí) → 席地而坐 (xí dì ér zuò)
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