This is the 472nd most frequent Icelandic word.
einum
The Icelandic word "einum" is the dative singular form of "einn," meaning "one" in English.
Here, 'einum' is used as a masculine singular dative definite article to match the word 'vini' (friend) in the sentence, emphasizing the friend being referred to.
Ég gaf vini mínum einum lítinn gjöf.
I gave my friend a small gift.
In this sentence, 'einn' is used as an adjective meaning 'alone' or 'by oneself' to describe the subject 'hann' (he).
Eftir að bíll hans bilaði var hann einn að lenda í vandræðum.
After his car broke down, he was left alone dealing with the trouble.
Here, 'einum' is used in the dative case as an adjective that qualifies 'fulltrúa' (representative), meaning 'one' to specify the quantity of the representatives.