Ignore words are for words that the team wants included in the spellcheck, but are not needed in the lexicon, cluttering search. Borrowed words from other languages and transliterations can be stored as ignore words.

Ignore words are tagged with /! in hunspell, and the default affix file interprets this as "no suggest". That means the spell check in Libre Office will accept the word, but will never suggest it as a spelling for a misspelled word.

This feature is entirely optional and some teams may not see a need for it.