B1
something you say or write to say that you are sorry about something you have done
Dictionary examples:
My dog ate my homework, so I wrote an apology to my teacher. (0.0)
I wrote an apology letter to the library for returning a book covered in pizza. (0.0)
I owe my boss an apology for accidentally sending him a funny cat video. (0.0)
"Was he at all sorry for what he'd done?" "Oh he was full of apologies." (15.2)
I owe you an apology, Chris. (28.0)
I have an apology to make to you - I'm afraid I opened your letter by mistake. (31.4)