noun
beaming smile; radiant smile
Describes a bright, cheerful, and open smile that conveys happiness or relief. Often used in literary or descriptive contexts.
彼女の晴れやかな笑顔を見て、私も嬉しくなった。
Seeing her beaming smile made me happy too.
合格発表の後、彼は晴れやかな笑顔で教室を出た。
After the exam results were announced, he left the classroom with a radiant smile.
晴れやか is a na-adjective meaning 'bright' or 'radiant' and can modify other nouns, but 晴れやかな笑顔 is a fixed compound with its own entry.
Compound of 晴れやか (bright, radiant) and 笑顔 (smile). The exact historical derivation is uncertain, but the phrase is conventionally used to describe a particularly bright and cheerful smile.