Unwise means not showing good judgment or common sense. An unwise decision is one made without thinking carefully about what might go wrong or what the consequences could be.

Spending your entire allowance on candy the day you get it would be unwise, because you'd have nothing left for things you might need later in the week. It's unwise to wait until the night before a big test to start studying, or to ignore storm warnings and go swimming anyway. When you make an unwise choice, you're usually choosing what feels good right now over what would actually be better for you.

The opposite of unwise is wise, and the difference matters. A wise person thinks ahead, considers different outcomes, and learns from experience. An unwise person might ignore good advice, rush into decisions, or repeat the same mistakes. Notice that being unwise isn't the same as being unintelligent. Smart people sometimes make unwise choices when they let emotions override their judgment or when they simply don't pause to think things through.