In a manner relating to mirrors or reflection; according to the principles of catoptrics and the behavior of reflected light.
From catoptrical + -ly (adverbial suffix). Transforms the adjective into an adverb describing how something occurs or is studied.
Scientists might describe how light behaves 'catoptrically' when bouncing off a mirror—it's a technical way to signal 'this is about reflection, not refraction.'
Complete word intelligence in one call. Free tier — 50 lookups/day.