expression, noun-modifying (irregular)
relieving; refreshing; satisfying
Describes a feeling of relief or satisfaction, often when a frustrating situation is resolved or justice is served. Used prenominally, as in 胸のすく思い.
彼の活躍を見て、胸のすく思いだった。
Seeing his success was truly satisfying.
胸のすくようなニュースを聞いた。
I heard some refreshing news.
胸がすく is a verb phrase meaning 'to feel relieved/refreshed', while 胸のすく is its prenominal form used to modify nouns.
From 胸 (chest/heart) + の (possessive particle) + すく (to become clear/refreshed). The expression likely derives from the idea of one's chest feeling clear or unblocked.