This is the 9030th most frequent German word.
letzterer
"Letzterer" means "the latter" in English.
The word 'letzterer' refers to the latter mentioned option, in this case, 'eine Katze'.
Ich habe einen Hund und eine Katze; letzterer schläft meistens tagsüber.
I have a dog and a cat; the latter mostly sleeps during the day.
Here 'letzterer' refers to 'Birne', introduced after 'Apfel'.
Zwischen Apfel und Birne bevorzugt sie letzterer, da sie süßer ist.
Between an apple and a pear, she prefers the latter because it is sweeter.
In this sentence, 'letzterer' refers to 'Österreich' as the latter mentioned country from the previous statement.