noun
straight-line distance; as the crow flies
Refers to the shortest distance between two points, ignoring terrain or roads. Often used in contrast to actual travel distance.
駅までの直線距離は短いが、実際に歩くと遠回りになる。
The straight-line distance to the station is short, but it's a long way around when you actually walk.
When I measured the straight-line distance on the map, it was about 5 kilometers.