flywheel

n heavy wheel revolving on a shaft to keep a machine operating at an even speed 飞轮; 惯性轮.

flycatcher, flyer, flying, flying buttress, flying colours, flying column, flying doctor, flying fish, flying fox, flying jump (also flying leap), flying officer, flying picket, flying squad, flying start, flying tackle, flying visit, flyleaf, flyover, flysheet, flyweight, FM, FO, foal, foam, foamy, fob, focal, focal length (also focal distance), focal point, focsle, focus, focus on, focus...on, fodder, foe, foetal (US fetal), foetus (US fetus), fog, fog-bank, fog-bound,