A conformation of a saturated cyclic molecular entity, containing an even number (≥8) of atoms in the ring, in which these atoms lie alternately in each of two parallel planes and are symmetrically equivalent (D4d for cyclooctane, D5d for cyclodecane etc). It is analogous to the chair conformation of cyclohexane.
See also: tub conformation
PAC, 1996, 68, 2193. 'Basic terminology of stereochemistry (IUPAC Recommendations 1996)' on page 2205 (https://doi.org/10.1351/pac199668122193)