Synonymous with a synclinal alignment of groups attached to adjacent atoms.
See: torsion angle
Sources:
Blue Book, p. 484 (https://www.acdlabs.com/iupac/nomenclature/)
PAC, 1996, 68, 2193. 'Basic terminology of stereochemistry (IUPAC Recommendations 1996)' on page 2209 (https://doi.org/10.1351/pac199668122193)