On Sat, 05 Dec 2015 15:03:36 +0000, e27002 aurora
wrote:

On Fri, 4 Dec 2015 03:36:30 +0000, "Clive D. W. Feather"
wrote:

In message , Neil Williams
wrote:
(I realise, definitely with an S rather than a Z, that there is a US
cross-post on this thread, though)

The OED actually prefers the Z spellings, as they derive from a Greek
form with a zeta in it ("izon", IIRC). The S spellings are something
else to blame on the French.

:-)