hinder
To make something more difficult or slow it down.
To hinder means to make something harder to do or to slow down progress. When a heavy backpack hinders your running in PE class, it weighs you down and keeps you from moving as fast as you could. When rain hinders a baseball game, play has to stop or slow down because of the weather.
Think of hinder as putting obstacles in the way of success. Poor lighting might hinder your ability to read. A noisy classroom can hinder concentration during a test. If you're trying to finish your homework quickly but your little brother keeps interrupting with questions, he's hindering your progress, even if he doesn't mean to.
The opposite of hindering is helping or advancing. A good teacher helps rather than hinders learning. Sometimes we accidentally hinder ourselves: staying up too late can hinder your performance at school the next day.
Notice that hinder doesn't mean completely stopping something, just making it more difficult or slower. The rain might hinder the baseball game, but with determination, the players might still finish. When you recognize what's hindering you, whether it's distractions or poor planning, you can often find ways to overcome those obstacles.