To unclog means to remove something that's blocking a pipe, drain, or other passage so that things can flow through again. When a kitchen sink gets clogged with food scraps and stops draining, someone needs to unclog it, maybe by using a plunger or carefully removing what's stuck. When your nose is stuffed up during a cold, taking a hot shower might help unclog your nasal passages so you can breathe easily again.

You might unclog a vacuum cleaner hose when too much dust builds up inside, or unclog a shower drain when hair accumulates over time. Sometimes people use special tools like plungers or drain snakes to unclog pipes, while other times running hot water or using specific cleaners does the job.

The word can also be used more broadly: if traffic has been backed up on a highway due to construction, opening a closed lane helps unclog the roadway. Understanding how to prevent and fix clogs, whether in plumbing or elsewhere, is a useful practical skill that saves time, money, and frustration.