Homing, in this sense, is about an animal’s gift for finding its way back. A bird or animal with a homing instinct can travel a long way — sometimes hundreds of kilometres — and still reach home, even across land or water it has not seen before. Homing pigeons are the famous case: people used them to carry messages because the bird would fly back to its own loft. Salmon coming back to the river where they were born are another picture of the same idea. Scientists still argue over exactly how it works — the sun, the stars, the Earth’s magnetic field, smell — and it is honest to say there is not one tidy answer. You will also hear homing on missiles and other machines that “find” a target; that is a later, borrowed picture from the animal idea. Here the word is about the living creature going home.