Is it der, die or das Böller? – der Böller, plural die Böller

Why is it der Böller?

Böller ends in -er, and most nouns ending in -er are masculine: in a German dictionary, 86% of them take der.

Sense 1

der

[1] Small fireworks that create a loud bang, but no special lighting effects

[1] kleiner Feuerwerkskörper, der einen lauten Knall, aber keine besonderen Lichteffekte erzeugt

[2] Device with which salute shots are given on solemn occasions

[2] Gerät, mit dem zu feierlichen Anlässen Salutschüsse abgegeben werden

[1] Thousands of rockets and firecrackers are lit on New Year's Eve
[1] In der Sylvesternacht werden abertausende Raketen und Böller gezündet.

[1] "In the back yard, a firecracker goes into the air"
[1] „Im Hinterhof geht ein Böller in die Luft.“

More source examples (1)

These dictionary examples can include historical and less common uses.

[2] The firecrackers were ready, only the bride and groom were missing
[2] Die Böller standen bereit, es fehlte nur noch das Brautpaar.