だてじゃなかったです
伊達じゃなかったです
datejanakattadesu

Noun
Desu Copula
na-Adjective

The polite, past negative form of だて

1. It wasn't as it seemed.; It wasn't for show.; It wasn't superficial.

Past/Perfective
Negative
Polite
Casual Register
Usually Written in Kana