Ise Or Ize?

[pinstripe]

Apologise or apologize? A colleague swears that the ize ending is the correct spelling and was taught that at school. (This is English not American by the way)
Which is the correct historical usage ?

[Jackdaw33]

A lot depends on the meaning and origin of the word. If the suffix is merely used in the sense of 'to make', e.g. rationalise, to make rational, then either is correct. If, however , the whole word is derived from a French or Latin word, such as 'advertise', then usually only 'ise' is acceptable.