Dictionary flashes up and closes immediately

[MkkDdd]

This is probably due to recently installing OSX.15.3: selecting text, then right-clicking mouse and clicking Look Up "[selected text]" brings up the dictionary pop-up, but only for a fraction of a second before it disappears. This seems to be system-wide, e.g. same thing happens in Google Chrome, in Pages, Finder, Preview, etc.
Any suggestions solutions most gratefully received.

 

[Peadogie]

I had the same thing happen on my Catalina 10.15.3 clean install. Dictionary was not preinstalled, although the icon was in the Applications folder. I had to go to/open Applications>Dictionary.app.
Dictionary will download it. Seemed a bit strange, but it worked.