1. A guiding star, a star that shows the way, particularly Polaris, the North Star.
2. A guiding light, a principle by which we may set our course in life.
It is an old derivative from the ancestor of lead "to guide, direct, show the way", the same source as load. The original meaning of lode is "road, way", a path that leads somewhere. It also turns up in other words and phrases like lodestone "magnetic iron", a substance that leads pieces of steel toward it. The phrase the mother lode, referring to a major vein of some valuable metal, also relies on the sense of something long and narrow leading somewhere. Back in the 16th century a lodesman was a guide or boat pilot, again, a kind of leader.