noun
coasting; freewheeling
Technical term for moving without power, especially in vehicles or machinery. Often used in engineering and transportation contexts.
電車が惰行で駅に近づいた。
The train coasted into the station.
エンジンを切って惰行運転する。
Cut the engine and coast.
Compound of 惰 (だ, 'laziness, inertia') and 行 (こう, 'going, travel'). The term is a modern technical coinage, likely from the early 20th century, referring to coasting or freewheeling motion.