Not clean in the way that keeps people healthy — dirty enough that germs can grow and spread, so it may make someone ill. This is a health word, not a beauty word. A kitchen towel that has been wet for three days may look fine, but it is unhygienic. A room can be untidy and still be perfectly hygienic; a room can look tidy and still be unhygienic. Books piled everywhere: messy, not unhygienic. A chopping board used for raw chicken and then for salad without washing: unhygienic. The word is a bit formal and a bit official. You hear it from health inspectors, in news reports about restaurants, on notices in hospitals and food factories. In ordinary talk between friends, people usually just say dirty, or gross, or that's disgusting. If your friend drops a sweet on the floor and eats it, saying "that is unhygienic" sounds like you are reading from a government report — which is exactly why people sometimes say it as a joke, in a stiff voice. It is also softer than dirty in one way: dirty can sound like an insult to the person, while unhygienic points at the practice or the place. A restaurant owner would be much less angry to hear "the conditions were unhygienic" than "your kitchen is filthy", though the two mean nearly the same thing. Note that it usually describes conditions, places, and practices — kitchens, water, habits, storage — rather than people themselves.

不衛生的