1Filled with a bittersweet, aching sadness — the tight, wistful pang in the chest brought on by longing, unrequited love, parting, or nostalgia. A quintessentially Japanese feeling with no exact English equivalent.
好きな人に会えない日が続くと、胸が切なくなる。
When the days I can't see the person I love pile up, my heart aches.
この歌のメロディーはどこか切なくて、聴くたびに泣きそうになる。
There's something wistful about this song's melody — it nearly brings me to tears every time.
子どもの頃を思い出すと、なつかしくて少し切ない。
Remembering my childhood fills me with nostalgia and a faint ache.
遠くで暮らす恋人を思うと、切なくてたまらない。
Thinking of my partner living far away, the longing is almost unbearable.
2Oppressive or suffocating; a physical tightness that feels crushing (short of breath, chest constricted). In modern usage this literal 「suffocating」 sense is much less common than the poignant sense above.
高熱で息が切なく、一晩中よく眠れなかった。
With a high fever my breathing was labored, and I couldn't sleep well all night.
煙が立ちこめて息が切なくなり、慌てて外に出た。
Smoke filled the room until it grew hard to breathe, and I hurried outside.