Foul

The foul rag that he used to clean the car only made it dirtier.

The foul odor from the chemical spill lingered in the air for days.

The experiment went foul, resulting in inaccurate data.

The car's engine started running foul, causing it to sputter and stall.

The old sailor taught the young boy how to make a foul.

The foul haze in the city made it difficult to breathe.

The foul smoke from the burning forest obscured the sun and created a gloomy atmosphere.