parallax
PAIR-uh-laks
Seeing the same thing from two slightly different positions and using the difference to judge distance. Your two eyes do it automatically. Astronomers do it with Earth's orbit. The word names the principle that perspective is never singular — every position reveals something the last one hid.
Etymology
Greek parallaxis, alteration, from parallassein, to change, to alternate. The change that comes from shifting your position.
*
Surprise Me With a Word