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-uelo, -elo, -illo, -iello, -el Diminutive suffix.

From Latin -olus, -ellus, -illus, -lus 'id.' All from original Latin suffix -ulus 'id.' The vowel changes and consonant additions were due to sound conditioning (see explanatory quote by Penny below). From Proto-Italic *-elos. From Proto-Indo-European *-elo- 'id.'

Romance: Western Vulgar Latin: Asturian -uelu, Portuguese -ulo, Galician -ulo, Catalan -ul, French -ule, Italian -olo; Eastern Vulgar Latin: Romanian -ul

Italic: Oscan kaíla "sacred building" and Faliscan cela "small storeroom" contain Proto-Italic *-elā

Indo-European: Celtic: Welsh -el, Breton -el; Germanic: Old Icelandic -ull, Old English -l, Old High German -ala,

"[The suffix] -uelo is now most frequently pejorative in tone and may have diminutive value.... Its Latin antecedent -OLUS, was at first inherently atonic, ... and was applied to forms which displayed hiatus between the two final syllables: FILIUS → FILIOLUS, FLUVIUS → FLUVIOLUS. Under such phonological conditions, spoken Latin transferred the stress from the antepenultimate to the penultimate syllable..., thus converting the suffix from atonic to tonic and ensuring its continued identity.... The suffix -uelo was very frequent in Old Spanish and apparently retained the affectionate value of its Latin ancestor." ~ R. J. Penny, A History of the Spanish Language (2002)
uh (Interjection) "ugh"

Of expressive origin. No further etymology possible.
últimamente (Adjective) "lastly"

From ultimo and -mente, an adjective-forming suffix.
ultimar (Verb) "to finish"

17th cent. From Latin ultimare 'id.,' from ultimus "last" (see último).
último (Adjective) "last," "final"

15th cent. From Latin ultimus 'id.' From Proto-Italic *ol-tamo 'id.,' from Proto-Indo-European *h2ol-tmHo- "furthest." From the root *h2el- "that" (see el (2), él).

Romance: Western Vulgar Latin: Portuguese último, Catalan últim, French ultime, Italian ultimo; Eastern Vulgar Latin: Romanian ultim

Italic: Oscan últiumam "last"

An ancient comparative with *h2ol-tero- "further" (whence ultra).
ultra (Adverb) "beyond"

15th cent. From Latin ultra 'id.' From Proto-Italic *ol-tero- 'id.,' from Proto-Indo-European *h2ol-tero- "further." From *h2ol- "that" (see el (2), él).

Romance: Western Vulgar Latin: Portuguese ultra, French outre, Italian oltra

An ancient comparative with *h2ol-tmHo- "furthest" (whence último).
umbría f. (Adjective, Noun) "shady;" "shady place"

From Latin umbra "shadow." From Proto-Italic *unfrā- 'id.' Perhaps from Proto-Indo-European *Hu̯nskr-eh2- 'id.' but the phonology and semantics are troubling and the putative root *Hu̯enk- is uncertain.

Romance: Western Vulgar Latin: Asturian sombra, Portuguese sombra, Catalan ombra, French ombre, Italian ombra; Eastern Vulgar Latin: Aromanian umbrã, Romanian umbră; Sardinian: umbra

Indo-European: Balto-Slavic: Lithuanian unksmė̃ "shade"
un (Indefinite Article) "a"

An apocopated form from uno.

Romance: Western Vulgar Latin: Asturian unu, Portuguese um, Galician un, Catalan un, French un, Italian uno; Eastern Vulgar Latin: Aromanian un, Romanian unu; Sardinian: unu
uni- Prefix "one"

From Latin uni- 'id.' From unus "one" (see uno).
único (Adjective) "only," "unique"

Late 15th cent. From Latin unicus 'id.' From unus "one" (see uno) and -icus, diminutive sufix (see -ico).

Romance: Western Vulgar Latin: Portuguese único, Catalan únic, French unique