-in die
Schwägerin
Always 99.4% of the 471 common nouns ending in -in take die.
Add -in to a man's job or nationality and you get a woman: der Lehrer, die Lehrerin. Always feminine.
Exceptions der Muffin
die Schwägerin
It's die Schwägerin. Schwägerin is feminine, plural die Schwägerinnen.
Meine Schwägerin heißt Fatima.
My sister-in-law is called Fatima.
Schwägerin
Always 99.4% of the 471 common nouns ending in -in take die.
Add -in to a man's job or nationality and you get a woman: der Lehrer, die Lehrerin. Always feminine.
Exceptions der Muffin