корпеть

Etymology
Related to, from , from , via semantic shift: to patch → to work → to work hard, to pore over. Related to 🇨🇬, 🇨🇬, 🇨🇬, 🇨🇬, 🇨🇬.

Verb

 * 1)  to work hard/meticulously/thoroughly (on something), to pore over, to plug away