Definition
The inward turning of the eyes toward each other when focusing on a near object. The brain uses the angle between the two lines of sight to judge how far away the object is, providing one of the cues for depth perception at close range.
Plain English
When you look at something close to your face, your eyes turn slightly inward to point at it. Your brain reads how much they had to turn and uses that to judge distance.
Context Anchor
Encountered in discussions of pilot vision, depth perception, visual cues, and landing judgment.
Derivation
From Latin bini ('two at a time') + oculus ('eye'), and convergere ('to incline together'). So literally 'two eyes leaning toward each other' — which is exactly what the eyes physically do when focusing on something close.
Why Pilots Care
Accurate binocular convergence supports reliable depth perception when judging runway distance on final approach.
Analogy
Hold a finger close to your nose and look at it. You can feel your eyes turn inward; that inward turn is the kind of cue binocular convergence describes.
Intuition Check
Do not confuse “binocular” here with handheld binoculars. Here it means both eyes working together.
Example Sentence 1
Because binocular convergence is only effective at short range, a pilot judging the distance of approaching traffic must rely on size and motion cues rather than the eyes' angle.
Example Sentence 2
During the medical exam the doctor checked binocular convergence to confirm the applicant could perceive depth correctly.