The phrase "ill wind" is an idiomatic expression that means a situation or person who causes trouble, harm or misfortune. It can also refer to any unpleasant or unfavorable circumstance or event. The origin of this phrase lies in the fact that strong winds can cause damage and destruction, such as knocking things over or causing power outages. Therefore, when someone says "ill wind," they are implying that a particular situation or person is bringing about negative consequences just like how a strong gust of wind can bring down trees or topple objects.