No rule for this one
No ending or word group predicts the article of Stewardess. Learn it as a pair and say it out loud: die Stewardess.
die Stewardess
It's die Stewardess. Stewardess is feminine, plural die Stewardessen.
Die Stewardess hilft mir.
The flight attendant helps me.
No ending or word group predicts the article of Stewardess. Learn it as a pair and say it out loud: die Stewardess.