noun
sharp parting remark; cutting farewell words
A harsh or dismissive remark made when parting, often with a sense of finality or rejection. The kanji 棄 (to discard) reinforces the idea of throwing away words as one leaves.
彼女はすてことばを残して部屋を出ていった。
She left the room, leaving behind a sharp parting remark.
別れ際にすてことばを投げつけるのはよくない。
It's not good to hurl cutting words at someone when parting.
Compound of 棄 (すて, 'discard') + 言葉 (ことば, 'words'). The exact historical derivation is uncertain, but the word is formed from the verb 棄てる (to throw away) and 言葉, suggesting words that are cast aside as one departs.