reverse curve

reverse curve (plural reverse curves)

1. A curve to the left or right which immediately curves in the opposite direction, and which is basically S-shaped.
   • 1959 November, G. H. Robin, “Railways to Helensburgh—a pre-electrification retrospect”, in Trains Illustrated, page 544:

     Some slight alterations in alignment were necessary to provide the pier line and the station is approached by severe reverse curves in both directions.

• S-bend

• “reverse curve”, in Lexico, Dictionary.com; Oxford University Press, 2019–present.