Foul

The hiker lost his way in the foul mist that enveloped the mountains.

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

The hikers lost their way in the foul mist of the dense forest.

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

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