Supine (-tum)

The supine is a verbal noun (the act of loving, warning, ruling, hearing are the meanings of the above four); its use will be explained later (12.1/3). In verbs with regular principal parts it is formed by adding -tum to the present stem, with the modification of e to i in the second conjugation (mone- > moni-). …

My impression is that the supine is one of the more irregular parts of speech.

When a supine comes over to English, the suffix “-tum” turns into “-tion”. Here are some examples I like.

sedeo	I sit	sessum	session
dico	I speak	dictum	diction
informo	I inform	informatum	information
moveo	I move	motum	motion
traho	I pull	tractum	traction

By the way, there are lots of things in Latin that end in “-um”; the supine is just one of them.

Now, having put the word “information” in the table above, I want to say a few words about it. The original verb, “informo”, is made up of the prefix “in-” and the verb “formo”, and so has something to do with forming. Here's how my Latin dictionary defines it.

to form, shape; to sketch (in words), give an idea of; to instruct, educate

My English dictionary says pretty much the same thing about the word “inform”, except for one little entry at the end.

To impart information to.

So, it seems to me that the word “information” is no longer really just a part of speech, it has gone and acquired a life of its own.