Here are 4 etymologies that I found:
1.1 Origin early 15c., from Fr. origine, from L. originem “rise, beginning, source,” from oriri “to rise” (http://www.etymonline.com/index.php?l=o&p=10)
1.2 Middle English origine < Latin origo (“beginning, source, birth, origin”) < oriri (“to rise”) (http://en.wiktionary.org/wiki/origin)
1.3 Origin 1350–1400; ME < L orīgin- (s. of orīgō) beginning, source, lineage, deriv. of orīrī to rise (http://dictionary.reference.com/browse/origin)
1.4 Origin “Definitions: descent, ancestry XIV; point or place of beginning XVI. - F. origine
or L. origo, origin-, f. oriri rise. So original: pertaining to origin (first of o.
sin XIV); sb. +origin; pattern, exemplar XIV; singular or eccentric person XVII. -
(O)F. original or L. originalis. origination XVII. - F. - L. originatio derivation
of words, f. pp. stem of *originare, whence originate (-ATE) XVII.” [Based on:
Oxford Concise Dictionary Of English Etymology (1996 paperback version), p. 326] (http://mirrorh.com/u.htm)
The first three etymologies indicate that the word origin was derived from the latin noun origo f (http://en.wiktionary.org/wiki/origo) which in turn was derived from the verb oriri.
For this to occur one would have to take the stem of the verb oriri and then add the suffix -go to get origo f, although I can’t find a source confirming this to be a possibility which is a worry.
Where did the consonant g come from in the word origo, was g part of a common suffix used to form nouns at the time, or is there something else going on in the formation of the noun origo? On that issue the last part of the fourth etymology can perhaps shed some light “- L. originatio derivation of words, f. pp. stem of *originare.”, where the Latin verb originare is mentioned.
As a result it could be that there were two latin verbs oriri and originare.
Originare is only listed in wiki as an Italian verb (http://en.wiktionary.org/wiki/originare), although I found the Latin originare mentioned again regarding the etymology of the word originate:
“< Medieval Latin *originatus, pp. of *originare (“to begin, originate”) < Latin origo (“origin”); see origin” (http://en.wiktionary.org/wiki/originate).
Thus it is unclear if origin is actually derived from oriri or originare, nor is it clear which gender the suffix -gin or -in refers to.