noun
supplement; top-up; making up a deficiency
Used for something that fills a gap or makes up for a shortfall, often in the phrase 足しになる (to be helpful as a supplement).
See also: 足しになる
少しでも足しになればと思って、お金を渡した。
I gave him some money, hoping it would help even a little.
この収入は家計の足しになる。
This income helps supplement the household budget.
Kana spelling is common in everyday writing, especially when the kanji is not needed.
Derived from the verb 足す (たす, 'to add'), nominalized as 足し. The kanji 足 carries the meaning of 'sufficiency' or 'adding'.