Terminology.
A true "virus" has never been successfully released into the wild for OS X and spread. That's a fact. "Virus" has a precise definition, having to do with what it does and how it does it. You're welcome to not care, but be aware that "virus" is only one type of malware.
There is plenty of other malware that applies to Mac OS X. Virtually all of it actually attacks the USER not the OPERATING SYSTEM. Users are not immune to doing dumb things.
However, in the common parlance, all sorts of things are called "viruses". Wrongly. You don't call an 18-wheeler a "car". You don't call baseball "football".
Or I dunno, maybe you do. Meh.
>>However, in the common parlance, all sorts of things are called “viruses”.<<
Well, I used to teach debate and if you own the terms, you own the round.
So we should accept your definition because...?