Which is why I'm guided by the appearance or form of things rather than by nomenclature.

In old photos and paintings we can't know what names people had for things. We can only see their appearance. So you might have to pardon me at times for following the "if it walks like a duck and quacks like a duck it's a duck" mindset.

In the photo of the man at that wedding I can see not a stitch that he's wearing that is different from what all the Highland Dress catalogues at that time were calling "Day Dress". So we know what the people he probably bought his kit from called it; what he called it himself we cannot know; what we call it today is our own concern.