In my legal-writing class last Thursday night, we were discussing "nominalizations": verbs converted into nouns by adding a suffix. For example, assume becomes assumption; decide becomes decision. The problem arises when we try to convert these nouns back into verbs, not by stripping the suffix, but by adding more words. Thus, instead of writing assume, we write make an assumption; instead of writing decide, we write make a decision as to. The lesson was to try to write with the base verbs: don't write "The court made a decision as to the case," when you can write, "The court decided the case."
Anyway, to make my point, I boldly stated that every English-language word ending in -tion or -sion contains a base verb. My students quickly pointed out several words ending in -tion that, at first glance, don't appear to have a verb base: section, lotion, notion, and potion.
Back at the office, I consulted OED Online, and found that all I was right after all -- it's just that the base verbs are Latin, not English. What's more, all four words can serve as either a noun or a verb.
The verb section means to divide into sections, or to cut through so as to present a section. The noun section is based on the Latin verb secare (to cut).
The verb lotion means to treat with lotions. The noun lotion is based on the Latin word lotio (the act of washing) and the Latin verb lavere (to wash).
Notion too is both a noun and a verb. The verb notion means to divide into several categories or sections, or to conceive, imagine, or envisage. The noun notion comes from the Latin words notio and noscere. (The dictionary doesn't say what noscere means, but I'm sure it's a verb.) The noun notion shares its etymology with the English verbs note and notify.
The verb potion means to treat or dose with potions, or to drug. The noun potion comes from the Latin potio (a drink) and potare (to drink).
I doubt that the verbs section, lotion, notion, and potion prove the point I tried to make in class. Those verbs seem to spring from nouns, rather than the nouns being built on the verbs. But the Latin base verbs do prove my point, although with a qualification. I still know of no English-language word ending in -tion that isn't built on a verb. It's just that somewhere in the language's evolution, the verb form may have gotten lost.