sadness associated with some wrong done or some disappointment
"he drank to drown his sorrows"
"he wrote a note expressing his regret"
"to his rue, the error cost him the game"
Emotional pain on account of something done or experienced in the past, with a wish that it had been different; a looking back with dissatisfaction or with longing.
"She felt deep regret every time she remembered her harsh words to her sister."
In plain English: Regret is feeling sad because you wish you had done something differently.
"She felt deep regret when she realized she had missed her friends' wedding."
feel sad about the loss or absence of
"She felt deep regret at the sudden loss of her childhood home to fire."
To feel sorry about (a thing that has or has not happened), afterthink: to wish that a thing had not happened, that something else had happened instead.
"After thinking about his careless words, he felt deep regret and wished he could take them back."
In plain English: To regret something means to feel sad about an action you already took because it was wrong or didn't turn out well.
"I regret missing your birthday party because I wanted to see you so much."
Usage: Use "regret" as an intransitive verb when expressing sorrow for past actions without directly affecting the object of your sadness. Avoid using it transitively with future events or hypothetical situations where you simply mean to disapprove; instead, use phrases like "I regret that..." followed by a clause describing what happened.
The word regret comes from the Old French verb meaning "to lament." It ultimately traces back to ancient roots related to weeping and making sounds of sorrow.