mainstay; pillar of support; person one relies on
Metaphorical expression for a person who is an indispensable support, like a walking stick or pillar. Often used in formal or literary contexts.
He worked hard as the mainstay of his family.
My grandmother was an emotional pillar for me.
Compound of 杖 (つえ, 'cane, walking stick') and 柱 (はしら, 'pillar'). The combination figuratively denotes a person who serves as a support, like a cane or pillar.