https://doi.org/10.1351/goldbook.C01422
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 ( for cyclooctane, for cyclodecane etc). It is analogous to the chair conformation of cyclohexane. 

See also: tub conformation