noun
A metal fastener shaped like a staple, driven into two pieces of wood to hold them together. Used in carpentry and construction.
大工さんが木材をかすがいで固定している。
The carpenter is securing the timbers with a clamp.
noun
Metaphorical use: something that binds two people or things together, like a relationship or shared interest. Often appears in the phrase 子はかすがい (children are a bond between parents).
共通の趣味が二人のかすがいになった。
Their shared hobby became a bond between them.
子はかすがいと言うけれど、本当にそう
noun
Rare use referring to a latch or lock mechanism. In modern Japanese, 錠 (じょう) or ロック is more common.
古い文献では、かすがいが戸締まりの金具を指すことがある。
In old documents, かすがい sometimes refers to a metal fitting for locking a door.
They say children are a tie that binds, and I really think so.
Originally a carpentry term for a metal staple. The metaphorical sense comes from the idea of holding things together firmly. The kanji 鎹 is a 国字 (kokuji) created in Japan.