Adverse means harmful, unfavorable, or working against you. When conditions are adverse, they make things harder or more dangerous than they should be. A ship facing adverse weather might encounter storms, high winds, or fog that threaten the voyage. A hiker in adverse conditions might struggle through heavy rain, extreme cold, or difficult terrain.

In medicine, doctors watch for adverse reactions to medications: unexpected problems like rashes, dizziness, or stomach pain that harm rather than help the patient. In court, lawyers might face an adverse ruling when a judge decides against their argument.

The word captures the feeling of pushing against something that pushes back. Think of riding your bike into a strong headwind: that's an adverse wind. Or imagine preparing for a math competition only to discover the questions cover topics you haven't studied yet: those are adverse circumstances.

Adverse is related to adversary, which means an opponent or enemy. Both words share the sense of opposition: an adversary works against you, while adverse conditions work against your success. When something is adverse, it's standing in your way, making your goal harder to reach.