The word 'nasties' is a colloquial term used to describe something unpleasant, unwholesome or disgusting. There are several synonyms that can be used in its place including foul, noxious, putrid, offensive, revolting, repulsive, vile, horrid, obnoxious and hideous. These words all convey a sense of disgust or repugnance towards something, whether it be an odor, taste or appearance. In everyday language, people may use the word 'nasties' to describe a range of things, from a bad smell to a contaminated surface. By using a different synonym, it can help to add variety to your language and express yourself in different ways.