with great vigor; in leaps and bounds; like surging waves
Idiomatic phrase describing rapid, powerful progress or momentum, often used for growth, success, or unstoppable force. The literal image is of raging waves.
The new product is selling like hotcakes.
He rose through the ranks with astonishing speed.
怒涛 alone means 'raging waves' or 'surging billows'; 怒涛の勢い is the full set phrase meaning 'with the force of surging waves'.
勢い by itself means 'force', 'momentum', or 'vigor'; the phrase 怒涛の勢い intensifies this with the image of raging waves.
Standard modern spelling using 涛 (simplified form).
Traditional spelling with 濤; still seen but less common than 涛.
Compound of 怒涛 (raging waves) + の (possessive particle) + 勢い (force, momentum). The phrase evokes the unstoppable power of surging waves.