No Thank You
No Thanks
expression
結構 is something like "fine" or "alright." This is just a little more polite. You can use this to say no thank you to someone trying to offer you something.
けっこうです
The reading comes from 結構.
いいえ、結構です。夕食はいりません。申し訳ありませんが、ストレスで食欲がないんです。
No, that’s okay. I don’t want dinner. Sorry, but I’m so stressed that I have no appetite.