knowing no bounds; showing no signs of stopping
Set phrase used to describe something that continues relentlessly, often in a negative or overwhelming sense (e.g., inflation, ambition, violence).
His ambition knows no bounds.
The rise in prices shows no signs of stopping.
Kana spelling is common for this set phrase; the kanji forms are also used but less frequent.
Kanji spelling using 止 (stop).
Kanji spelling using 留 (stay/remain).
A set phrase combining とどまる (to stop/stay) + ところ (place) + を (object marker) + 知らない (does not know), literally 'does not know a place to stop'. The exact origin is uncertain, but it follows a classical Japanese pattern of idiomatic expressions.