switchback

n 1 (esp Brit) = roller-coaster (roller). 2 zigzag railway or road for ascending or descending steep slopes （上下陡坡的）之字形铁路或公路.

swing, swing bridge, swing shift, swing-boat, swing-door, swing-wing, swingeing, swipe, swirl, swish, Swiss, Swiss chard, Swiss roll, switch, switch off, switch on, switch-blade, switch-man, switch-over, switch-yard, switchboard, switched-on, Switzerland, swivel, swizz, swizzle, swizzle-stick, swollen, swoon, swoop, swoop down on, swop, sword, sword-dance, sword-play, sword-stick, swordfish, swordsman, swordsmanship, swore,