Questions & Answers about Vinsæla appið er mjög gott.
Why is the adjective vinsæla used instead of the basic neuter form vinsælt?
Because it comes directly before a definite noun (appið - the app). When an adjective describes a definite noun and sits right next to it, it must use the weak declension. The weak ending for neuter singular adjectives is -a.
This lesson is about the weak plural ending -u. How would we say 'The popular apps are very good'?
In the plural, weak adjectives end in -u regardless of gender. So 'the popular apps' becomes Vinsælu öppin. The full sentence would be Vinsælu öppin eru mjög góð. Notice that the first adjective gets the weak -u, but the one after the verb (góð) uses the strong plural form.
If vinsæla is weak because the app is definite, why does gott use the strong form?
Because gott is separated from the noun by the verb er (is). When an adjective comes after a verb like 'to be', it always uses the strong declension, even if the subject of the sentence is definite. gott is the strong neuter singular form of góður (good).
Is appið just the English word 'app'?
Yes! Icelandic frequently adopts modern technology words directly. It was adopted as a neuter noun (app), so it gets the standard neuter definite article -ið attached to the end to mean 'the app'.