unavoidable
Not able to be stopped or avoided from happening.
Unavoidable means impossible to prevent or escape, no matter what you do. When something is unavoidable, it's going to happen whether you like it or not.
Some things in life are truly unavoidable. Growing older is unavoidable. Making mistakes while learning something new is unavoidable. If you're running late and stuck in traffic caused by an accident ahead, the delay is unavoidable: there's simply no way around it.
You might hear someone say “it was unavoidable” when explaining why something unfortunate happened despite their best efforts to prevent it.
Be careful not to confuse truly unavoidable situations with ones that just feel that way. When a student says homework is unavoidable, they're right: it has to be done. But when they claim getting a bad grade was unavoidable, that might not be true. With enough preparation and effort, that outcome might have been avoided. The difference matters: recognizing what's truly unavoidable helps you focus your energy on the things you actually can control.