"Stiff fines" refers to harsh or severe penalties that involve paying a large amount of money as a punishment for breaking a rule or law. Full definition
Anyone convicted of a white collar crime not only face stiff fines and imprisonment sentences, but also face an uncertain future regarding their career. (manuelianlawfirm.com)
Compliance can be encouraged by implementing stiff fines for failing to obtain and wear a licence tag. (humanecanada.ca)
Companies that exceed their permits must buy extra allowances from those companies who have managed to reduce their emissions - or pay stiff fines. (foeeurope.org)