1) American musical duo 2) CBC Television show 3) Zigzag on a hike 4) Zigzag trail up a mountain 1) Ess 
one of many sharp turns in roads that go up steep mountains.
A course design that results in the dog making continual 180-degree turns.
an established hiking trail that zigzags across steep terrain. Switchback A zigzagging trail up the side of a steep ridge, hill or mountain, which allows for a more gradual and less strenuous ascent.
a piece leaves a square, and then later in the solution returns to it by the same route (for example, a rook moves e3-e5-e3). Compare with round trip, in which the route taken back to the original square is circuitous.
A sharp turn in a trail (usually constructed on a slope of more than 15%) to reverse the direction of travel and to gain elevation. The landing is the turning portion of the switchback. The approaches are the trail sections upgrade and downgrade from the landing.
when the trail turns tightly on a climb and goes back on itself. Also known as a hairpin.
A tight, zigzag turn on the face of a mountain, either uphill or downhill.
Climbing a mountain or hill with a zig-zag motion. This allows for a significantly easier ascent in many situations.
a highway, as in a mountainous area, having many hairpin curves. · a zigzag track arrangement for climbing a steep grade. · See
A hairpin turn; British.