The Negative Additive Clitic -kaan / -kään
Just as you use the clitic -kin for "also" or "too" in affirmative sentences, Finnish uses a different clitic for negative sentences: -kaan or -kään. It translates to "either" or "neither".
Like other suffixes, it follows vowel harmony rules. Use -kaan for words with back vowels (a, o, u) and -kään for words with front vowels (ä, ö, y) or only neutral vowels (e, i).
Because it expresses a negative addition, the sentence must always include a negative verb (en, et, ei, emme, ette, eivät). Attach the clitic to the end of the word you are emphasizing.
Using -kaan / -kään with Case Endings
The clitic always goes at the very end of the word. If the word has a case ending, such as in the "I have" structure (minulla on), the clitic attaches after the ending to become minullakaan.
You can also attach it directly to demonstrative pronouns like tämä (this):
The Pronoun "Kumpikaan"
To specifically say "neither one" when referring to two things or people, use the pronoun kumpikaan. It already contains the -kaan suffix and pairs with the negative verb.
Emphasizing Other Words
You can attach -kaan / -kään to almost any part of speech to show what else is not happening or true. For example, attaching it to a noun emphasizes that an expected state or feeling is also absent.