Something that is accurate is exact and true. It's important to be accurate in the kitchen with your measurements and in the courtroom with your testimony.
The adjective accurate comes from the Latin roots ad curare, meaning "to take care," and that is precisely what you do when you make sure something is accurate. You take care to make sure it is perfectly correct: an accurate answer, an accurate headcount, an accurate assessment of the problem. By adding the Latin root in, meaning not, you can make the antonym inaccurate (not accurate).