Searches Google matches to a keyword though they're worded differently: misspellings, plurals, reordered words, synonyms and the same intent.
Google doesn't match keywords letter for letter. Every match type, exact included, also reaches close variants, and there's no setting to turn them off. Google's list includes misspellings, singular and plural forms, stemmings, abbreviations, accents, reordered words with the same meaning, function words, implied words, synonyms, paraphrases, and searches with the same intent.
For a brand this cuts both ways. Your own exact match keyword catches the misspellings of your name without you listing them. But a publisher's keyword can reach your name too: a phrase match on “discount code” can show on “yourbrand discount code” because the search includes the keyword's meaning.
Negative keywords don't follow. Google says they don't match close variants, though it says they account for casing and misspellings. Plurals and synonyms have to be added by hand, which is why a brand's required negatives should list more than the one right spelling.
In the search terms report, a search reached this way shows a match type such as Exact match (close variant). Round the edges shows how this carries ads onto code searches.
Google's own help and policy pages first.