noun
things left undone; unfinished business
Refers to tasks, work, or matters that remain incomplete or were not done. Often used with a sense of regret or as a reminder.
今日中にやり残しを片付けなければならない。
I have to take care of the things I left undone today.
やり残しがないように、リストを確認しよう。
Let's check the list so that nothing is left undone.
やりかけ emphasizes something started but not yet finished, while やり残し focuses on things that were never done or were left undone, often with a nuance of omission.
Compound of the verb stem やり (from やる 'to do') and 残し (from のこす 'to leave behind').