to cure, to heal
乿 centers on restoring order or health: curing illness and healing what is broken. The idea is bringing something back to a proper, settled state.
乿 is a rare character whose exact historical development is uncertain. It visually combines 爫 (claw/hand), 糸 (thread), and 乚 (a hook shape), but the original semantic and phonetic roles of these components are not clearly established.
Picture a hand (爫) carefully untangling a knotted thread (糸) with a small hook (乚), straightening it out to cure the tangle and heal the mess.
For チ, imagine a tiny hand using a hook to heal a thread, and the whole scene is as small as a cheese crumb: cheese -> チ.