Curved recurved, Revertant, Reverted, Vertant, Verted

Bent and rebent like the letter S. Also blazoned vertant and revertant or verted and reverted. 

Revertant was sometimes used for a bending in the manner of a chevron.

For similar terms or variations, see also Annodated, Bowed, Embowed,  Flected, Rebending, Recurvant, Reflected, Reflexed, Torgant, and Torqued.