Definition: The word "apheliotropic" refers to a phenomenon where light, heat or pressure are directed at an object that causes it to undergo different effects than if they were not present. Definition: - An object that has been subjected to forces (such as a lens) and can only respond in the presence of those forces is said to be "apheliotropic." - This term comes from the Greek word for "light" or "heat." - An object that experiences different effects based on its position relative to light, heat, or other objects is said to be "aphelotropic." - In this case, a lens is an example of an object that can only respond in response to light. The term comes from the Greek word "apheliotrope," which means "to turn through." This term emphasizes the phenomenon's ability to change its appearance or direction under certain conditions.