Informal describes something relaxed, casual, and free from strict rules or ceremony. When you wear informal clothes, you might choose jeans and a t-shirt instead of a suit or dress. An informal gathering with friends means you can show up without fancy preparation, just ready to hang out and have fun.

The word often contrasts with formal. A formal dinner might require specific table manners and dress codes, while an informal lunch lets everyone relax and be themselves. At school, an informal discussion means students can share ideas freely without raising hands or following rigid turn-taking rules.

In language, informal words and phrases are the ones you use with friends and family but might avoid in school essays or speeches. Saying “kids” is informal; “children” is more formal. “Yeah” is informal; “yes” is formal. Neither is wrong; they just fit different situations. Understanding when to be informal and when to be formal is part of learning to communicate well in different contexts.

The word can also mean unofficial or not following standard procedures. An informal agreement between classmates to trade lunches doesn't involve written contracts, just a friendly understanding between people who trust each other.