crown conformation

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 (D 4d for cyclooctane, D 5d for cyclodecane etc). It is analogous to the chairconformation of cyclohexane.
See also: tub conformation
PAC, 1996, 68, 2193 (Basic terminology of stereochemistry (IUPAC Recommendations 1996)) on page 2205