rhumb line

American  

noun

1. a curve on the surface of a sphere that cuts all meridians at the same angle. It is the path taken by a vessel or aircraft that maintains a constant compass direction.

---

rhumb line British  

noun

1. an imaginary line on the surface of a sphere, such as the earth, that intersects all meridians at the same angle

2. the course navigated by a vessel or aircraft that maintains a uniform compass heading

---

Etymology

Origin of rhumb line

First recorded in 1660–70

Example Sentences

Before the days of GPS, sailors often charted nautical courses using what’s called a rhumb line.

From Slate • Jan. 21, 2026

The wind held long enough for the boats to slip through, and a half-hour later we were sailing a rhumb line for the beach.

From New York Times • Dec. 16, 2019

To ensure that every cartouche, sea monster and rhumb line remains vibrant, the men keep the Venetian blinds in their south-facing apartment drawn, as if for a permanent siesta.

From New York Times • Jan. 23, 2014

Finally, a light breeze filled in and we made what turned out to be a terrible decision to stick close to the rhumb line and sail north of San Nicolas Island, past some rock outcroppings.

From Time Magazine Archive

By using the plotter and its �highway� feature, you can maintain position on the rhumb line, which is the original course you intend to run.

From Time Magazine Archive