Poorly means in a way that's inadequate, unsatisfactory, or not done well. When you perform poorly on a spelling test, you get more answers wrong than right. When a soccer team plays poorly, they miss passes, lose possession, and fail to score. When someone explains something poorly, their explanation confuses rather than clarifies.

The word describes results that fall short of what's expected or needed. A poorly written essay might have good ideas but be full of grammar mistakes and unclear sentences. A poorly planned birthday party might run out of food or have nothing for guests to do. Notice that poorly doesn't always mean terribly: something done poorly might just be mediocre or below average rather than a complete disaster.

In British English, poorly can also mean sick or unwell. Someone might say “I'm feeling poorly today” when they have a cold or stomachache. This usage is less common in American English, where people typically say “I'm feeling sick” or “I'm not feeling well.”

The opposite of poorly is well: a well-executed plan, a well-written story, or a test done well.