How can I quit frozen Spotlight without rebooting my computer?

Depending on your OS and luck, it could actually be 1 of at least a few [services]:

• mds
• SystemUIServer
• Spotlight

To me, a while back when they were called feline names, I've had the same issue (as I was saying on the comments) and it was not Spotlight: it was the Menubar. Just like with spotlight, we simply have to kill it so it will be restarted by launchd.

For that, use the Activity Monitor and search for your [service].

Or you may instead use the Terminal, for instance:

killall Spotlight

And if that doesn't work, consider using sudo.

Just ran into Spotlight itself crashing. The answer for that problem is just going to the Terminal and typing:

killall Spotlight

Fixed the Spotlight freeze problem!

The first post is correct that mds is the process for spotlight. You can kill it in activity monitor or:

sudo killall mds

from the terminal. The process will restart automatically as it is managed as a launchd item that is set to always be running.

You might look at

man mdutil

as well. This is a utility at the command line for managing mds settings on volumes.