IPA: /rɪˈɡrɛtəbl/
KK: /rɪˈɡrɛtəbl/
Causing sadness or disappointment; something that is unfortunate or should not have happened.
It was a regrettable mistake that could have been avoided.
Regrettable → It is formed from "regret" (from Latin "regretare", meaning to weep again or lament) and "-able" (meaning capable of being). The word "regrettable" means something that is capable of causing regret or lamentation.
Think of feeling sad about something that can cause you to 'weep again' — that's why 'regrettable' refers to something that causes regret.