Plain English Meaning

A tiny needle-like point sitting in a small jewel cup, used as a bearing so something can spin or swing very easily. In a compass, it's what lets the compass card turn smoothly to point north.

Full Definition

A low-friction bearing arrangement in which a hardened, sharply pointed pivot rests in a small cup-shaped jewel (typically synthetic sapphire or ruby), allowing a delicate moving element to rotate freely with minimal resistance. In a magnetic compass, the float carrying the compass card is suspended on a jewel-and-pivot bearing so the card can swing freely to align with the Earth's magnetic field.

Context Anchor

Seen in descriptions of the magnetic compass and how the compass card is supported inside the instrument.