re·gret
[ri-gret]
verb, -gret·ted, -gret·ting, noun

verb (used with object)
1. to feel sorrow or remorse for (an act, fault, disappointment, etc.): He no sooner spoke than he regretted it.

2. to think of with a sense of loss: to regret one’s vanished youth.

noun
3.a sense of loss, disappointment, dissatisfaction, etc.

4.a feeling of sorrow or remorse for a fault, act, loss, disappointment, etc.

5.regrets, a polite, usually formal refusal of an invitation: I sent her my regrets.

6.a note expressing regret at one’s inability to accept an invitation: I have had four acceptances and one regret.