intransitive verb.
To feel sorry, disappointed, distressed, or remorseful about.
intransitive verb.
To remember with a feeling of loss or sorrow; mourn.
intransitive verb.
To feel regret.
noun.
A feeling of sorrow, disappointment, distress, or remorse about something that one wishes could be different.
noun.
A sense of loss and longing for someone or something gone or passed out of existence.
noun.
A courteous expression of regret, especially at having to decline an invitation.