detain v. detention

abstain v. abstention

this transform from the verb form to the noun form is kind of alien to me.

Hope someone can give more examples to try to complement this category of words.

tks

As Mr. Micawber has mentioned, this transform is no longer productive in modern English.
There are hundreds of such Latin roots which occur in such pairs.  It would probably be impractical to try to learn all the patterns.  Nevertheless, if that sort of thing interests you, you might try keeping a list of verb-noun-pair patterns together with the particular verbs which fall into each pattern.

Some roots remain the same, simply adding "tion" (compact, compaction), but there are many possible patterns.
You may find these interesting.  Some add a syllable with "a" before adding "tion"; some add the "tion" or "sion" right after the verb root.  Most often all the verbs with the same root, but different prefixes, all form the noun the same way.

direct, direction (correct)
translate, translation (promote)
combine, combination (exhale, commute, permute)
condemn, condemnation (affirm, transport)
receive, reception (deceive)  (eiv > ep)
redeem, redemption (eem > emp)
decide, decision (d > s)
erode, erosion (d > s)
conclude, conclusion (d > s)
expand, expansion (d > s)
exclaim, exclamation (ai > a)
pronounce, pronunciation (ou > u) (announce, denounce)
conjoin, conjunction (oin > unc)
reduce, reduction (produce, deduce, induce)
expel, expulsion (repel, compel, propel) (el > ul)
admit, admission (it > iss) (permit, commit, submit)  [dismiss, dismissal!]
repeat, repetition (ea > e)  (adds "ition", not the more usual "ation")
apply, application (y > ica) (comply *, reply *, imply)  (*The verb and the noun have little in common where meaning is concerned!)
acquire, acquisition (r > s) (require)

How many more can you find? 

CJ