to lean on a support, and so to rely on someone or something for security
At its root this word is physical: to put your body weight on something that holds you up, a staff, a wall, or another person's hand. If that prop gives way, you fall. Everything else the word means grows out of that picture.
From there it moves naturally to reliance. To lean on a person or a power is to make it the thing that keeps you standing, to stake your safety on it. The Hebrew keeps the bodily image alive underneath, so "trust" in this word is never a purely mental attitude: it is the whole self resting its weight on something and expecting it to bear the load.
Because the image is so concrete, the prophets use it to expose misplaced confidence. The same act of leaning is praised when the support is God and condemned when it is anything else:
- Judah leans on horses and chariots instead of on the LORD (Isaiah 31:1)
- Judah leans on Egypt, a splintering reed that pierces the hand that grips it (Ezekiel 29:7)
- the powerful lean on injustice and lies to prop up their rule (Isaiah 30:12)
A close relative, בָּטַח, names trust as felt confidence and security; this word pictures that same trust as the act of resting one's weight on a prop. Another neighbor, סָמַךְ, covers the physical leaning and laying of weight even more broadly.