I noticed an advert on TV advertising "unmissable" shows coming up. MS Word marks it as a spelling mistake, but the Mac OS is OK with it.
I don't particularly like it.
English Language & Usage Stack Exchange is a question and answer site for linguists, etymologists, and serious English language enthusiasts. It only takes a minute to sign up.Sign up to join this community
You probably have to update your MS-Word. Unmissable is a word that can be found in most dictionaries. It is a pretty boring word but we can't deny the fact that it is used by some people.
Words can be invented. If it uses a root that people are familiar with and affixes that are understandable then people will know what you are saying, although it might sound weird. Sounding unusual might be what they are striving for. I know what unmissable would mean and I could put it in a sentence of my own, so why not? If you don't like, then that is probably a good enough reason to avoid it.