The prefix over- attaches to the front of words to mean “too much” or “excessively.” When you overcook pasta, you leave it boiling too long and it turns mushy. When a parent is overprotective, they worry and restrict their child more than necessary. When you're overwhelmed by homework, you have more than you can reasonably handle.

Notice how over- changes the meaning: cooking becomes overcooking, confidence becomes overconfidence, and thinking becomes overthinking. The prefix turns a neutral or positive action into something excessive or problematic.

Sometimes over- means “above” or “across” rather than “too much.” An overpass is a bridge that goes over a road. An overcoat is worn over other clothes. An overview looks at something from above, giving you the big picture rather than tiny details.

The “too much” meaning is more common, though. When your teacher says you overestimated how much time you'd need for an assignment, you guessed too high. When you overreact to a minor problem, you respond more dramatically than the situation requires. The prefix helps us describe when something crosses the line from enough to too much.