でたらめじゃありませんでした
出鱈目じゃありませんでした
detaramejārimasendeshita

Noun
Desu Copula
na-Adjective

The polite, past negative form of でたらめ

1. It wasn't nonsense.; It wasn't arbitrary.; It wasn't made up.

Past/Perfective
Negative
Polite
Terminal Form
Usually Written in Kana