Definition
Light that reaches an object or surface after being reflected from another surface, rather than traveling directly from its source. In aircraft instrument panel design, indirect lighting refers to illumination provided by lamps positioned so the light bounces off the panel face or a diffuser before reaching the pilot's eyes, rather than shining directly at them.
Plain English
Light that bounces off something before you see it, instead of coming straight from the bulb. In a cockpit, this means the lamps are hidden or angled so the light spreads softly across the panel without glare.
Context Anchor
Seen in discussions of cockpit lighting, cabin lighting, instrument panel lighting, and night flying.
Derivation
Indirect comes from Latin in- ('not') and directus ('straight'). Light that is not traveling in a straight path from source to eye -- it has been redirected first.
Why Pilots Care
Direct light in the cockpit at night ruins night vision and creates glare on instrument glass. Indirect lighting lets the pilot read instruments clearly while keeping the eyes adapted to the dark outside.
Analogy
Like a bedside lamp pointed at the ceiling instead of at your face -- the room is lit, but nothing is shining in your eyes.
Intuition Check
Indirect light does not mean dim light or unimportant light. It means the light is not aimed straight at the thing being viewed or directly into the pilot’s eyes.
Example Sentence 1
The instrument panel uses indirect light from shielded lamps along the glareshield, so the pilot can read the gauges at night without losing dark adaptation.
Example Sentence 2
Overcast skies produce indirect light that softens shadows on the runway during landing.