Whaaattt?

I still use what are now called almost, or sometimes fully, archaic words. That is mainly because I enjoy being bloody awkward .

As I have come late to this topic I shall only put in a groat's worth of comments and particularly eschew any modern terminology.

With regard to using 'in' and 'un' in prefixes of words it can also be the difference between whether it is being used as an adjective or adverb - as is the case with the original question posed by @ViewAhead. Nowadays most of those words are considered interchangeable.

There are times when having to write or respond to officious officials I tend to use overly long words or shorter archaic ones. In those sort of situations I particularly enjoy using words such as shew instead of show.

Many years ago I received what I considered an overly officious missive from the DHSS. So I replied using extremely long and little used words which elicited a polite request for me to translate it for them. They ended up by demanding that I send them copies of some papers from three years previous because they were unable to find their copies. They became quite threatening over it. So I complained to my MP (a customer of mine) and ended up with an apology from the Minister.