Regrettable; disappointing; unfortunate—used when an expected or desired result was not achieved.
試合に負けてしまって本当に惜しかった。
We lost the match; it was really a pity.
時間がなくて話したいことを全部言えなかったのが惜しい。
It's a shame I couldn't say everything I wanted because there wasn't enough time.
惜しいミスでチャンスを逃した。
We missed the chance because of an unfortunate/avoidable mistake.
Precious; dear; something you don't want to let go of, or a feeling that you don't want to waste time/money (e.g., 'time is precious').
今日はやることが多くて時間が惜しいから、手短に話すね。
I have a lot to do today and can't waste time, so I'll be brief.
その古い写真は家族にとって惜しいものだ。
That old photo is precious to the family.
Used in the pattern '〜には惜しい' to mean someone or something is too good for a given position or situation—deserving better.
彼の才能はこの小さな会社には惜しい。もっと大きな舞台が向いている。
His talent is too good for this small company; he's suited for a bigger stage.
この絵は美術館に飾るには惜しいほどの逸品だと言われた。
They said this painting is such a masterpiece that it's almost too good for display in a museum. (i.e., it deserves a better place)
Almost but not quite; 'so close'—used when something nearly succeeded or was nearly achieved but ultimately failed.
彼はゴール直前でシュートを外して、惜しくも勝利を逃した。
He missed his shot right before the goal and narrowly missed winning.
惜しい！あと0.1秒早ければ世界記録だったのに。
So close! If only 0.1 seconds earlier, it would have been a world record.
答案は全部合っていたが、マークがずれていて惜しくも不合格だった。
All answers were correct, but the marks were misaligned and, close as it was, he failed.