kǔ​kǔ

persistently

苦苦 kǔ​kǔ
persistently adverb
with great effort, tenacity, or insistence despite difficulties

He begged the boss hard for another chance.

painful descriptive
marked by extreme bitterness, hardship, or suffering

After struggling in poverty for many years, he finally lived a good life.

Frequency

Movie subtitles
3.34 per million appears in 2% of films
Written text
7.59 per million

Sources

Definitions
CC-CEDICT