众所周知
zhòng suǒ zhoū zhī · HSK 7
see 眾所周知|众所周知[zhong4 suo3 zhou1 zhi1]
📢 众 crowd + 所 that-which + 周 all-around + 知 know = what the whole crowd knows
Four-part chengyu: 众 (crowd/everyone) + 所 (that which) + 周 (whole/all-around) + 知 (know). Literally what the entire crowd knows all around, hence as everyone knows or it is common knowledge.
所 — door 戶 (left) + axe 斤 (right)
Originally a sound: an axe (斤) chopping wood near a door (戶), with 戶 also hinting at the pronunciation. Over time it was borrowed to mean 'place' or 'location,' and later became a grammatical particle nominalizing verbs ('that which…'). The concrete 'chopping' sense faded entirely.
周 — enclosure 囗 + 吉 (earth 土 + mouth 口)
Originally a pictograph of a field with grain plotted in rows, suggesting density and completeness. It came to mean 'all around,' 'circumference,' and 'complete,' later extending to 'week' (a full cycle). Also a major surname, famously the Zhou dynasty.