An irregularity is something that doesn't follow the normal pattern, rule, or schedule. When a teacher notices an irregularity in test scores, like one student's answers matching another's exactly, it suggests something unusual happened that needs investigation. When doctors find an irregularity in a heartbeat, they mean the heart isn't beating in its normal, steady rhythm.

The word often appears when people are checking to make sure things are working as they should. An accountant might discover irregularities in a company's finances, meaning the numbers don't add up the way they're supposed to. Election officials watch for irregularities at polling places to ensure voting happens fairly.

An irregularity isn't always bad: sometimes it just means different from expected. A surface with irregularities has bumps and dips instead of being perfectly smooth. A bus schedule with irregularities might have some routes that run at odd times.

In grammar class, you learn about irregular verbs like “go” (which becomes “went” instead of “goed”). These verbs are irregular because they break the normal rules. When something shows irregularity, it stands out from the normal pattern, which can be either concerning or simply interesting, depending on what you're looking at.