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-on, -ón Augmentative suffix akin to "large."

From Vulgar Latin *-one 'id.' Of unknown origin. It is phonologically possible that it comes from Latin -onem, the accusative of -o, a suffix forming masculine nouns, however this is semantically difficult. If from Latin -o, then from Proto-Italic *-ōn- 'id.' From Proto-Indo-European *h3onh2- 'id.'

Romance: Western Vulgar Latin: Portuguese -ão
opción f. (Noun) "option"

18th cent. From Latin optionem, accusative of optio 'id.' From a hypothetical verb *opere "to choose." See optar for more information.

Romance: Western Vulgar Latin: Portuguese opção, French option, Italian opzione ; Eastern Vulgar Latin: Romanian opțiune
operación f. (Noun) "operation"

15th cent. From Latin operationem, accusative of operatio 'id.' Ultimately from operari "to operate" (see operar).

Romance: Western Vulgar Latin: French opération
operar (Verb) "to operate"

18th cent. From Latin operari 'id.' A verb formed from opus "work" (see obra).

Romance: Western Vulgar Latin: French opérer, Italian operare ; Eastern Vulgar Latin: Romanian opera ; Sardinian: oberare
opinar (Verb) "to opine"

Very late 15th cent. From Latin opinari 'id.' While it looks to be a derivation from Proto-Italic *op-eje- "to choose" (whence optar), the semblance is superficial. A putative **op-einā- only raises more problems than it solves. Of unknown origin.

Romance: Western Vulgar Latin: Portuguese opinar, French opiner
opinión f. (Noun) "opinion"

13th cent. From Latin opinionem, accusative of opinio 'id.' From the verb opinari "to opine" (see opinar).

Romance: Western Vulgar Latin: Portuguese opinião, French opinion, Italian opinione
oportunidad f. (Noun) "opportunity"

From Latin opportunitatem, the accusative case of opportunitas 'id.' From opportunus "opportune" (see oportuno).

Romance: Western Vulgar Latin: Portuguese oportunidade, Italian opportunità
oportuno (Adjective) "opportune"

From Latin opportunus 'id.,' from ob- "toward" and portunus "suitable." Portunus is from porto "gate" (see puerto).

Romance: Western Vulgar Latin: Portuguese oportuno, French opportun
optar (Verb) "to opt (for)"

Very late 16th cent. From Latin optare 'id.,' from *opere "to choose" and frequentive suffix -tare (see note under faltar). Latin opere is from Proto-Italic *op-eje- 'id.' From Proto-Indo-European *h1op-ei̯e- 'id.'

Romance: Western Vulgar Latin: Portuguese optar, French opter, Italian optare ; Eastern Vulgar Latin: Romanian optare

Italic: Oscan ufteis "of the wish," Umbrian upetu "he chose"

Indo-European: Indo-Iranian: Sanskrit ā́pa "has reached," Young Avestan āpa 'id.;' Anatolian: Hittite epp-zi "to grab," Cuneiform Luwian pii̯a- "to give," Lycian pije- 'id.'
orar (Verb) "to pray"

12th cent. From Latin orare 'id.' According to de Vaan (2014), a verb formed from Proto-Italic *ōs- "mouth" (for the sense evolution, compare English phrase "to mouth the words"). See ósculo.

Romance: Western Vulgar Latin: Portuguese orar, Galician orar, Catalan orar, Italian orare ; Eastern Vulgar Latin: Aromanian or, Romanian ura

Italic: Oscan urust "he will prosecute"

Indo-European: Celtic: Old Irish á "mouth;" Indo-Iranian: Sanskrit ā́s- "mouth," Avestan āh- 'id.;' Anatolian: Hittite aiš "mouth," Cuneiform Luwian āaš- 'id.'