From older Kienföhre.
Kiefer f (genitive Kiefer, plural Kiefern)
From Middle High German kiver, from Old High German kifer, from Proto-West Germanic *kebr, from Proto-Germanic *kebrą, from the perhaps onomatopoeic Proto-Indo-European root *ǵep- (“to chew, eat”), also the root of Käfer (“beetle”).
The noun is also neuter in Austrian German. In the North of the German language area it is always masculine.