A badd word and a new badd word.
Press F7. Choose Ignore All or Add to Dictionary. The next "badd" will be reported instead of the completion of the spell checking.
Laszlo Nemeth committed a patch related to this issue.
It has been pushed to "master":
fdo#73917 spelling dialog: don't report fully ignored words again
The patch should be included in the daily builds available at
http://dev-builds.libreoffice.org/daily/ in the next 24-48 hours. More
information about daily builds can be found at:
Affected users are encouraged to test the fix and report feedback.
Note: this problem was reported by Gábor Kelemen.