From Wiktionary, the free dictionary
Fest (“feast”) + Mahl (“meal”)
Festmahl n (strong, genitive Festmahles or Festmahls, plural Festmähler or Festmahle)
- feast (meal), banquet
- Synonyms: Festessen, Bankett
- “Festmahl” in Duden online
- “Festmahl”, in Digitales Wörterbuch der deutschen Sprache[1] (in German)