迅猛 (xùnměng): rapid and fierce

Meanings

Kējì fāzhǎn xùnměng, lìng rén mù bù xiá jiē.

Technological development has been so rapid and fierce that it's dizzying.

Hóngshuǐ xùnměng de yǒng rù cūnzhuāng.

The floodwaters surged into the village with violent speed.

memory

迅 (swift) + 猛 (fierce / ferocious) — think of a ferocious beast striking with lightning speed.

迅 xùn

猛 měng