'Fortuitous' in the sense of 'accidental' was the usual meaning until the Seventies or Eighties in Britain and still is among the educated. But I never tell other people how to use the language. My rules are for myself. I permit myself to comment, however, on a site such as this.

Porsche, I don't think my strictures about 'cohort' can be called an etymological fallacy since, as my research assistant Warsaw Will has pointed out, as recently as 1965 it was described as 'an American vulgarism'.

Incidentally, Will, the social sciences have a lot to answer for linguistically.

Decimated! Quite. An other one is 'fortuitous' which, some years ago, started to be misused for 'fortunate'. Originally, it meant 'accidental', pure and simple. A death could be 'fortuitous'. It didn't mean you were happy about it.
Some dictionaries cover their behinds nowadays by saying it means 'fortunately accidental', rather like 'serendipitous'.

It's true that some descriptivist dictionaries list the wrong use of cohort. But then, to misquote Mandy Rice Davies, they would, wouldn't they?

Another term that gets misused to mean a single person is 'cohort' which is a tenth of a legion or, more generally, any group of soldiers.

Yes, I'm intrigued also as to why Stephen Fry is 'erstwhile'. Maybe he's had a sex change and become 'Stephanie'.

It's 'jill' for the English too.

Will - I agree. There are all sorts of variations and changes in the development of language. What was 'fallacious' was the idea that words must be pronounced as spelled, with an emphasis on 'must'. Of course, sometimes pronunciation follows spelling and sometimes it doesn't.

The pronunciation awf'n is becoming old-fashioned and of'n or often is now usual. According to the OED the sounding of the t was not then recognized by the dictionaries. But that was before the speak-as-you-spell movement got under way, and as long ago as 1933 the SOED recorded that the sounding of the t was then frequent in the south of England . That would now be an understatement of its currency. The long-drawn-out joke in The Pirates of Penzance - 'When you said orphan did you mean a person who has lost his parents or often , frequently' - will soon be unintelligible to the audience.
Fowler's Modern English Usage. Second edition, revised by Gowers.

Fowler disliked the notion that words must be pronounced as spelled.