Learn Icelandic: Læknirinn skoðaði lit sársins. - The doctor examined the color of the wound.

This is the genitive (possessive) definite form, which translates to 'of the wound'. The base word is the neuter noun sár (wound). To say 'of a wound', you add -s to make sárs. To say 'of the wound', you add the neuter definite article -ins, resulting in sársins.

Why is there no word for 'of' in the sentence?

Icelandic doesn't usually need a separate preposition for possession or 'of' phrases. Instead, it uses the genitive case. The ending on sársins does all the work to mean 'of the wound', and it is placed immediately after the noun it describes (lit).

Why is the word for color lit instead of litur?

The color is the direct object being examined, so it must be in the accusative case. The base word is the masculine noun litur (color). In the accusative case, masculine nouns ending in -ur typically drop that ending, leaving just lit.

How is the word læknirinn put together?

It is the nominative masculine noun læknir (doctor) combined with the definite article for 'the'. Because the base word already ends in -ir, the standard article -inn is just attached directly to the end, making læknirinn.