It's generally referred to as "Anzac Day" in Māori, sometimes with the addition of "Aotearoa" to indicate the New Zealand context: "Anzac Day Aotearoa".
While there are Māori translations for some of the key concepts associated with Anzac Day, such as "whakamaharatanga" (remembrance) or "tangata whakamaharatanga" (veterans), there isn't a single Māori word that captures the full meaning and significance of the day.