This is the 15035th most frequent German word.
seltene
Rare.
Here, 'seltener' is used as an adjective to describe objects that are uncommon or unique.
Die Bibliothek hat eine Sammlung seltener Bücher.
The library has a collection of rare books.
In this sentence, 'seltener' qualifies the noun 'Vogel,' emphasizing its rarity.
Ein seltener Vogel wurde am See beobachtet.
A rare bird was observed at the lake.
Here, 'selten' is used as an adverb to describe the infrequency or uncommonness of occurrences.