na-adjective, noun
Rare term describing a person or manner that is completely open, without concealment or reserve. Often used in the phrase 開け広げに話す (to speak frankly/openly).
See also: 開けっ広げ
彼は開け広げに自分の意見を述べた。
He expressed his opinion openly and frankly.
開け広げな態度で接する。
To interact with an open and unguarded attitude.
More common colloquial variant with the same meaning; 開け広げ is rarer and slightly more literary.
Compound of 開け (ake, continuative form of 開ける 'to open') + 広げ (hiroge, continuative form of 広げる 'to spread'). The exact historical derivation is uncertain, but the combination suggests the idea of being wide open and unconcealed.