parallax

Where does the word "parallax" come from? It comes from Greek parallaxis, and was adopted directly into English (1580s).

Parallax’s story begins in Greek: parallaxis meant “an alteration, a change.” Literally an alteration, a change, from parallassein (to change). It reached English by 1580s as parallax. Settled as the astronomical term for an object's apparent shift when viewed from different positions. Today, parallax means the apparent change in an object's position when viewed from different points.

1. Stage 1 · Greek · ancient parallaxis "an alteration, a change", literally an alteration, a change, from parallassein (to change).
2. Stage 2 · English · 1580s parallax "the apparent shift of an object viewed from different positions", settled as the astronomical term for an object's apparent shift when viewed from different positions.