noun
addition; supplement; appendix; postscript
Refers to something added to the main content, such as an extra note, a supplementary item, or a postscript. Often used in writing or when giving extra information.
レポートに付け足しを書く。
I write an addition to the report.
手紙の最後に付け足しを加えた。
I added a postscript at the end of the letter.
Compound of 付け (tsuke, continuative form of 付ける 'to attach') + 足し (tashi, continuative form of 足す 'to add'). Literally 'attaching and adding'.