Learn Hardcore Icelandic: Krakkinn sér hundinn.

Krakkinn is in the nominative singular definite. In Icelandic, the nominative marks the subject of a clause, and here the suffix -inn indicates that it’s definite.

Why is the verb sér used here instead of something like sjáir?

The infinitive verb is sjá (“to see”), but it conjugates irregularly in the present tense:
• ég sé
• þú sérð
• hann sér
• við sjáum
• þið sjáið
• þau sjá
Thus, the 3rd person singular present form is sér (“he/she/it sees”), not sjáir.

What does hundinn mean, and why does it end with -inn instead of -urinn or -ur?

Hundinn is the accusative singular definite form of hundur (dog). After a transitive verb like sjá, the direct object takes the accusative case. Definiteness is shown by the suffix -inn, so:

hund = a dog (accusative singular indefinite)
hundinn = the dog (accusative singular definite)
(Note that the nominative singular definite of hundur is hundurinn, with an extra -ur-.)

Why doesn’t Icelandic use a separate word for “the” like English does?

In Icelandic (and some other Germanic languages), definiteness is encoded as a suffix on the noun rather than as a separate article. You’ll see patterns like -inn, -in, -ið added to the noun stem instead of placing the before it.

How would you say A kid sees a dog (both indefinite) in Icelandic?

Use the bare stems without definite suffixes:
• Krakki sér hund.
Here krakki = a kid (nom sg indefinite), hund = a dog (acc sg indefinite).

How would you form the question What does the kid see? in Icelandic?

Place the question word first and keep the verb in second position (the V2 rule):
• Hvað sér krakkinn?
Literally “What sees the kid?”, where hvað = what, sér = sees, krakkinn = the kid.