means A person (or vehicle) that makes a long journey, especially by sea or through space.

from From Old French 'voiage' (a journey, travel), itself from Latin 'viaticum' — provisions for a trip — built on 'via,' a road or way. So a voyager is, at root, someone carrying supplies down the road; over centuries the word drifted from dusty Roman highways to ocean crossings, and eventually to a NASA probe carrying its own gold-plated provisions into the dark.