Lacking all symmetry elements (other than the trivial one of a one-fold axis of symmetry), i.e. belonging to the symmetry @[email protected] \(C_{1}\). The term has been used loosely (and incorrectly) to describe the absence of a rotation–reflection axis (alternating axis) in a molecule, i.e. as meaning @[email protected], and this usage persists in the traditional terms @[email protected], @[email protected], @[email protected], etc.