This is the 11256th most frequent German word.
sitzer
"Sitzer" in German typically refers to a person or object that sits or is seated, such as a sitter.
Here, 'Sitzer' is used as a noun referring to 'a seat' or 'a place to sit', describing the armchair.
Dieser Sessel ist ein bequemer Sitzer.
This armchair is a comfortable seat.
In this usage, 'Sitzer' denotes something or someone who sits, applied here to a dog.
Der Hund ist ein treuer Sitzer vor der Haustür.
The dog is a loyal sitter in front of the door.
The term 'Zweisitzer' is a compound noun including 'Sitzer', referring to a two-seater couch.