You describe something as regrettable when you think that it is bad and that it should not happen or have happened.
例句
...an investigation into what the army described as a regrettable incident...对军方称之为令人遗憾的事件的调查It is regrettable that strike leaders seem intent on spoiling holidays.遗憾的是罢工领导人似乎决意要破坏节日的气氛。
英汉词典释义
adj.
令人遗憾的;使人懊悔的
His tiredness caused him to make a regrettable error.他由于疲劳而犯了个令人遗憾的错误。It is highly regrettable that the minister cannot be here in person.很遗憾,部长不能亲自出席。
英英词典释义
Adjective
1. deserving regret;
"regrettable remarks""it's regrettable that she didn't go to college""it's too bad he had no feeling himself for church"