na-adjective
meaningful; suggestive; with a hidden story
Describes a person, look, or remark that seems to carry an unspoken meaning or a hidden past. Often used when someone appears to know more than they are saying.
彼はいわくありげな笑みを浮かべた。
He gave a meaningful smile.
その古い家にはいわくありげな雰囲気が漂っている。
That old house has a suggestive atmosphere, as if it holds some secret.