Why does Spotlight think "CHROM" matches Chrome, but "CHROME" matches Calendar? This behavior has been consistent for months, maybe even years at this point, and I finally decided to make a screen recording of it just to have some verification that it's really happening.  The steps are:


Command-space to open Spotlight search.
Type the letters C, H, R, O, M, E in order with pauses.
For CH, CHR, CHRO, and CHROM Spotlight thinks the best match is Google Chrome...
But as soon as I add the final E, Spotlight thinks the best match is Calendar.
Delete the final E and Chrome comes back to the top of the list...
Re-type the E, and it's Calendar again.


Video evidence:  https://youtu.be/nkWuhXLrN1I

I just can't think of any rational text matching/lookup system in which this behavior makes sense.  What on Earth is Spotlight doing?
It is possible the Spotlight index has gone wonky and needs a rebuild. You should follow these instructions, extracted verbatim from this Apple Support document, and reindex the Macintosh HD volume:


Choose Apple menu () > System Preferences, then click Spotlight.
Click the Privacy tab.
Drag the folder or disk that you want to index again to the list of locations that Spotlight is prevented from searching. Or click the Add (+) button and select the folder or disk to add.
To add an item to the Privacy tab, you must have ownership permissions for that item. To learn about permissions, choose Help from the Finder menu bar, then search for “permissions.”
From the same list of locations, select the folder or disk that you just added. Then click the Remove (–) button to remove it from the list.
Quit System Preferences. Spotlight will reindex the contents of the folder or disk.