Abnormal means different from what is usual, typical, or expected. When doctors say a test result is abnormal, they mean it doesn't match the normal, healthy pattern they usually see. When a teacher notices abnormal behavior in class, like a usually quiet student suddenly shouting, something unusual is happening.

Scientists use this word carefully: abnormal snowfall means much more or much less snow than usual for that time of year. Abnormal tire wear on a car suggests something might be wrong with the alignment.

Understanding what's abnormal requires knowing what's normal first. A temperature of 102°F is abnormal for a healthy person but might be normal during the flu. Sleeping twelve hours straight would be abnormal for most adults but can be normal for a teenager going through a growth spurt.

The word is often used in scientific or medical settings to describe a deviation from a pattern. Abnormal results don't automatically mean something bad, just something that deserves attention or explanation. When mechanics find abnormal engine noise, when scientists observe abnormal weather patterns, or when you notice abnormal quiet in a usually noisy classroom, the word signals that something is different from the usual pattern.