Definition 1 of 2
Plain English Meaning
Landing short of where you meant to land. The aircraft comes down before it reaches the runway or the spot you were aiming for.
Full Definition
To touch down short of the intended landing point on a runway. An undershoot occurs when the aircraft's flight path falls below the planned approach path and the aircraft contacts the ground before reaching the runway threshold or selected aim point.
Context Anchor
Used during landing approaches, especially when judging whether the aircraft will reach the runway or selected landing spot.
Derivation
From 'under' (below) plus 'shoot' (to send forward toward a target). The image is of a projectile falling short of its mark — here, the aircraft falling short of the intended landing spot.