Learn Finnish: Koira ei herää. - The dog isn't waking up.

Herätä (to wake up) is a Type 4 verb. To build sentences with it, you first drop the -tä ending to get herä-, and then double the last vowel. That gives us the stem herää-. In negative sentences, we just place this stem exactly as it is right after the negative verb ei.

Wait, isn't herää also the affirmative form for "wakes up"?

Yes, it is! For Type 4 verbs, the third-person singular affirmative (like "he/she/it wakes up") and the negative stem (used after en, et, ei, etc.) look exactly the same. Because of this, koira herää means "the dog wakes up", and koira ei herää means "the dog doesn't wake up".

Why do we use ei here instead of another negative word?

In Finnish, the negative word "not" behaves like a verb and changes its form to match who is doing the action. Since the subject is koira (the dog), which is a third-person singular noun just like "he", "she", or "it", we must use the third-person singular negative verb ei.

The translation says "isn't waking up". Can this also mean "doesn't wake up"?

Yes, it means both! Finnish doesn't have a separate continuous tense like English does with "is doing" or "isn't doing". Therefore, ei herää translates to either "doesn't wake up" or "isn't waking up", depending entirely on the context of the situation.