N3 — outside your level filter
Is said whole, with nothing composed onto it and takes no だ／です, so there are no forms to conjugate.
とんでもないです
tondemonaidesunot at all, don't mention itN3expression
Example sentences2
とんでもないです、私は何もしていません。
tondemonai desu, watashi wa nani mo shite imasen.
Not at all — I didn't do anything special. neutral
え、とんでもないです、そんなに褒められると恥ずかしいよ。
e, tondemonai desu, sonna ni homerareru to hazukashii yo.
Oh, not at all — it's embarrassing when you praise me that much. casual