This is the 5543rd most frequent Japanese word.
かす
"かす" (kasu) means "to lend" in English.
In this sentence, 'かす' is used to mean 'to lend', referring to allowing another person to use an item temporarily.
友達に自転車をかした。
I lent a bicycle to a friend.
Here, 'かす' is employed in a polite request form, asking someone to lend an item.
その本をかしてくれませんか？
Could you lend me that book?
In this context, 'かす' indicates the act of lending something to another person, describing an experience of lending.