Definitions

1. noun

A small, usually star-shaped rock or boulder, especially one that has been worn smooth by the sea and is now stranded above the high-tide mark.

“The pebbles and the occasional large pelorus lay scattered along the beach.”

2. noun

A device, such as a compass, that is used to indicate direction or position, especially in navigation or surveying.

“The pelorus on the old sailing ship helped the sailors navigate through the dense fog.”