Why is it die Ermangelung?

Ermangelung ends in -ung, and nouns ending in -ung are feminine: in a German dictionary, 99% of them take die.

All nouns ending in -ung
Sense 1
die

Meaning

[1] Only in the absence in the absence, see there

[1] nur in der Wendung in Ermangelung, siehe dort

Examples

[1]

[1]

Declension

1 Singular Plural
Nominativ die Ermangelung —
Genitiv der Ermangelung —
Dativ der Ermangelung —
Akkusativ die Ermangelung —

Pronunciation

Dictionary entries include material from Wiktionary. Wiktionary