taint

A taint is a small amount of something unpleasant or unwanted that affects a larger whole. A drop of poison could be a taint in otherwise clean water.

When we talk about a taint, it's usually because something that was originally good or pure has become spoiled by some kind of influence or addition. For example, if a politician is accused of taking bribes, their reputation might get tainted by the scandal. If a beautiful view is marred by litter and pollution, the natural beauty could be said to be tainted too. The word can also refer to something that's not physically contaminated but still has an unpleasant effect - like a rumor that taints someone's good name.