Questions & Answers about Äidin auto on uusi.
Why is there a "d" in äidin if the word for mother is äiti?
To show possession (mother's), you add the genitive ending -n. Adding this ending triggers a common spelling rule called consonant gradation. Here, the strong consonant t in äiti softens to a weak d, making the word äidin.
How do we know it means "the mother's" when there is no word for "the" in the sentence?
Finnish doesn't have articles like "a" or "the". Depending on the context, äidin auto can mean "mother's car", "the mother's car", or even "a mother's car".
Why doesn't the word uusi change its ending to match äidin?
Adjectives only change to match the noun they are describing. Here, uusi (new) describes the car (auto), not the mother (äiti). Since auto is in its basic form, uusi stays in its basic form too.
Do I always have to put the owner before the thing they own?
Yes, when using the -n ending to show possession, the owner comes right before the thing they own. The word order in äidin auto works exactly like "mother's car" in English.