Learn Icelandic: Getur þú lengt bolinn aðeins? - Can you lengthen the t-shirt slightly?

In this context, aðeins means "slightly" or "a little bit". While you might already know it as meaning "only" or "just", using it here as an adverb of degree softens the request, making it sound more polite than asking someone to simply lengthen the shirt.

Why is the verb lengt used here instead of the infinitive lengja?

The verb geta (can or to be able to) is a special modal verb in Icelandic because it is followed by the supine form of the main verb, rather than the infinitive. The supine looks exactly like the neuter past participle, which is why we use lengt instead of the infinitive lengja.

Is the verb lengja (to lengthen) related to the adjective for "long"?

Yes! Lengja means "to make longer" and comes directly from the adjective langur (long). You will often see this pattern in Icelandic where a verb is formed from an adjective by changing the vowel (here, the 'a' shifts to an 'e').

Why does the word for t-shirt appear as bolinn?

Bolinn is the definite, accusative form of the masculine noun bolur (t-shirt). It is in the accusative case because it is the direct object receiving the action of being lengthened. Adding the definite article ("the") changes the ending from -ur to -inn.