This is the 15827th most frequent German word.
älteste
"Älteste" means "oldest" or "elder."
In this sentence, 'älteste' is an adjective in the superlative form, describing Anna as the student who is the most advanced in age in her class.
Anna ist die älteste Schülerin in ihrer Klasse.
Anna is the oldest student in her class.
In this example, 'älteste' functions as an adjective in the superlative form, used to highlight that this specific book is the most aged in the collection.
Das ist das älteste Buch in meiner Sammlung.
That is the oldest book in my collection.
Here, 'älteste' is used to indicate that the son being referred to is the eldest among his siblings, functioning as an attributive adjective.