The term is derived from two words:

Every instinct screamed run . But his grandmother’s voice echoed in his mind: “Never run from a backward ghost. It feeds on fear. Stand still. Close your eyes. Cover the back of your head.”

Together, they refer to the or buttocks . Unlike some more vulgar alternatives, "passa paththa" is generally considered a neutral or semi-formal way to refer to the backside in daily conversation. Usage and Context

The first half of the path was ordinary—crickets, frog calls, the rustle of palm fronds. But as he rounded the old banyan tree, the air changed. It grew cold and still. The lantern flame stood straight, as if frozen.

“Ayye?” Nimal called, voice trembling. “Show your face.”