ronge

/ʁɔ̃ʒ/ronger
1.
verbInd1stPresSing1,3

gnaw

nibble

bite (e.g., nails)

Le chien ronge un jouet en caoutchouc.

The dog is gnawing a rubber toy.

2.
verbInd1stPresSing1,3

eat away at

torment (figuratively, as with guilt or worry)

erode (figurative)

La culpabilité le ronge depuis l'accident.

Guilt has been eating away at him since the accident.