From Wiktionary, the free dictionary
From Gas (“gas”) + Maske (“mask”).
Gasmaske f (genitive Gasmaske, plural Gasmasken)
- gas mask (headgear)
Declension of Gasmaske [feminine]
- “Gasmaske” in Duden online
- “Gasmaske” in Digitales Wörterbuch der deutschen Sprache