  It is argued that the definition of quasicrystals should not include the
requirement that they possess an axis of symmetry that is forbidden in periodic
crystals. The term "quasicrystal" should simply be regarded as an abbreviation
for "quasiperiodic crystal," possibly with two provisos, as discussed below.
The argument is supported by theoretical as well as experimental examples of
quasicrystals without any forbidden symmetry.
