プログレッシブ和英中辞典(第4版)の解説
いわく【×曰く】
❶〔言うことには〕
聖書にいわく
the Bible says...
❷〔理由，事情〕a reason
いわくがあって
for certain reasons
これにはいわくがある
There is a story about it.
どうもいわくがありそうだ
There seems to be something behind it.
彼女はいわくありげな目付きで彼を見た
She cast a meaningful glance at him.
いわく言い難い
いわく言い難い魅力
(an) indescribable charm
事情は複雑でいわく言い難い
The situation is too complicated for words.
いわく因縁
a complicated story
彼はこの事柄のいわく因縁を聞かせてくれた
He told me how the whole matter had come about.
それについてのいわく因縁は何も知らない
I have no idea 「how it all got started [what lies behind it].
いわく付き
いわく付きの女
a woman with a past
家賃が安いと思ったらやっぱりいわく付きの家だった
I thought the rent was low, and, sure enough, I later found out that the house had a story behind it.