Inexact means not completely accurate or precise. When a measurement is inexact, it's close but not perfectly correct. If you estimate that your bedroom is about 12 feet long without actually measuring it, that's an inexact measurement: it gives a general idea but isn't perfectly accurate.

Science often deals with the difference between exact and inexact answers. When you calculate that 7 times 8 equals 56, that's an exact answer. But when you measure the width of your desk with a ruler and get “about 24 inches,” that's inexact because you might not be measuring from exactly the right spot.

The word doesn't mean wrong. An inexact answer can still be useful. Weather forecasts are inexact but they help you decide whether to bring an umbrella. When you tell someone “I'll meet you in about 10 minutes,” you're giving an inexact time, but it's good enough for making plans.

Some things are inexact by nature. Predicting how long it will take to finish homework is inexact because unexpected problems might slow you down. Other things can be made more exact with better tools or more careful work.