to put a computer program back onto a computer

I had to reinstall the operating system. 我不得不重新安装操作系统。

You will need to re-install the program to get the latest version.

to put furniture, a machine, a piece of equipment, etc. back into the position that it was in before and make it ready for use

The mechanic was able to reinstall the pistons without damaging the engine. 机械师能够在不损坏发动机的情况下重新安装活塞。

They intend to re-install the fittings to match the original design.

to put someone back into an important job or position

The new owners have plans to reinstall Sykes as chief executive.

Her supporters want to reinstall her as president. 她的支持者希望重新任命她为总统。