Questions & Answers about Þessi strákur er montinn og gortar mikið.
How could I use the prefix lang- here to say this boy is "by far the most boastful"?
The prefix lang- must attach to a superlative adjective. You would change the positive adjective montinn (boastful) to its superlative form montnastur (most boastful) and add the prefix to get langmontnastur. The sentence would then be: Þessi strákur er langmontnastur...
This sentence uses both montinn and gortar for boasting. Is there a difference between them?
They are very close in meaning and often used together for emphasis. Montinn is an adjective describing someone's character as "boastful," "cocky," or "show-offy." Að gorta is a verb specifically meaning "to brag" or "to boast" verbally.
How does the adjective montinn change if the subject were feminine, like stelpa (girl)?
Adjectives ending in -inn follow a specific declension pattern where they drop the second -n in many forms. For a feminine nominative subject, montinn becomes montin. The sentence would be: Þessi stelpa er montin og gortar mikið.
Why is mikið in the neuter singular form here when the subject is a masculine boy?