Learn Finnish: Märkä koira seisoi ulkona. - The wet dog stood outside.

The dictionary form is seisoa (to stand), which is a Type 1 verb. To make the past tense, we find the stem by dropping the final -a, giving us seiso-. Then we add the past tense marker -i. Because the stem ends in -o, the -i just sits next to it forming a diphthong, making seisoi.

Why doesn't seisoi have a personal ending at the end?

The subject of the sentence is koira (the dog), which is third-person singular. In the Finnish past tense, the third-person singular does not get an extra personal ending letter. The word stops right after the past tense marker -i.

Is ulkona related to the word ulos?

Yes! Both mean outside, but they are used differently depending on movement. You use ulkona when someone or something is stationary and already outside, like the dog standing here. You use ulos when there is movement from inside to outside, like a dog running out of a house.

Why does ulkona end in -na?