v. & n.
v.tr. (regretted, regretting) (often foll. by that + clause) 1 feel or express sorrow or repentance or distress over (an action or loss etc.) (I regret that I forgot; regretted your absence). 2 (often foll. by to + infin. or that + clause) acknowledge with sorrow or remorse (I regret to say that you are wrong; regretted he would not be attending).
n. 1 a feeling of sorrow, repentance, disappointment, etc., over an action or loss etc. 2 (often in pl.) an (esp. polite or formal) expression of disappointment or sorrow at an occurrence, inability to comply, etc. (refused with many regrets; heard with regret of her death). give (or send) one's regrets formally decline an invitation.
[ ME f. OF regreter bewail ]