The only free and comprehensive online etymological dictionary of the Spanish language
báculo m. (Noun) "staff"
16th cent. borrowing from Latin baculum 'id.' Of unknown origin. Borrowed from a non-Indo-European language with a root *bak(k)- "stick," "staff."
Indo-European
Romance
Portuguese báculo, Galician báculo, French bâcle, Italian bacolo
Celtic
Old Irish bacc "crooked staff," "hook" (< *bakko-), Old Welsh bach "hook," Old Breton bah 'id.,' Old Cornish bagh 'id.'
Germanic
Middle Dutch pegel "peg," Old English pægel "wine jug"
Balto-Slavic
Lithuanian bàkstelėti? "to thrust," Latvian bakstît? "to poke"
Hellenic
Ancient Greek βάκτρον (báktron) "stick" (< *bak-tro-), βακτηρία (baktería) "staff," "scepter" (< *bak-tér-)
Basque
Basque makila "walking stick," probably from Latin bacila "sticks," plural of baculum
"A more widely distributed (West Central) root for 'club' is *bak- (e.g. OIr bacc 'staff', Lat baculum 'staff', Grk báktron 'staff'; a Middle Dutch cognate pegge suplies NE peg); the initial b- has been explained either as the mark of a 'popular word' (i.e. one apparently used only in informal contexts and subject to the possibility of special phonological changes) or a loanword from some non-Indo-European language." ~ Mallory & Adams, The Oxford Introduction to Proto-Indo-European and the Proto-Indo-European World (2006)
bailar (Verb) "to dance"
13th cent. Borrowed from Old Occitan balar 'id.' However the appurtenance of -i- in the Spanish is inexplicable. Of note is Pyrenees dialect variant and Aragonese dialect variant bailar "to sway," from Latin baiulare "to carry a burden." Because a borrowing from Old Occitan is more likely than from a dialect oddball in Aragonese, and because the semantics in Occitan are identical to Spanish, it is easier to accept the theory that bailar is a loan from Old Occitan balar with an unexplained diphthongization. The native Old Spanish word for dancing was sotar (see jota (2)). Balar is from Latin ballare "to throw." Borrowed from Ancient Greek βάλλειν (bállein) 'id.' (see diablo).
Variants
Pyrenees balar "to sway," Asturian balar 'id.'
baile (1) m. (Noun) "dance"
Very early 14th cent. From bailar.
Also the origin of the surnames Bailes and Bailo.
baile (2) m. (Noun) "bailiff"
Borrowed from Medieval Latin baiulivus 'id.' From Latin baiulus "porter," "steward." Of unknown origin, likely borrowed from a non-Indo-European language with the form *bagjelos "carrier."
Indo-European
Romance
Italian baglio "beam," Romanian baieră "strap"
bajar (Verb) "to lower"
12th cent. From Vulgar Latin *bassiare 'id.' from Latin bassus "base" and Vulgar Latin verb-forming suffix -iare. See bajo.
Indo-European
Romance
Aragonese baxar, Leonese baixare, Asturian baxar, Catalan baixar
bajo (Adjective; Adverb) "short," "low"
13th cent. From Latin bassus "base;" "fat." Borrowed from Ancient Greek βαρύς (barys) "heavy," "low." From Proto-Indo-European *gwr̥h2-u- 'id.' From *gwreh2- "to be heavy" (whence grave).
Indo-European
Romance
Asturian baxu, Portuguese baixo, Galician baixo, Catalan baix, French bas, Italian basso
Italic
Latin gravis "heavy," Oscan bravús 'id.'
Germanic
Gothic kaurjos "heavy"
Indo-Iranian
Sanskrit gurú- "heavy"
bala f. (Noun) "bullet;" "ball"
13th cent. Borrowed from French balle 'id.,' itself borrowed from Italian balla "ball." From a Germanic source (compare English ball). Ultimately from Proto-Germanic *ballan- 'id.' From Proto-Indo-European *bhol-on- 'id.' From a root *bhel- that Kroonen (2014) hypothesizes meant "to swell up."
Indo-European
Italic
Latin follis "bag," "testicles"
Celtic
Gaulish ballo-, Old Irish ball "penis," Middle Welsh balleg "sack"
Hellenic
Ancient Greek φαλλός (phallós) "penis"
balero m. (Noun) cup-and-ball; (Uruguay) "intelligence"
From bala.
The sense of "intelligence" in Uruguay stems from an earlier use of the word for the head of a person, used in Argentina and Uruguay.
bañar (Verb) "to bathe"
12th cent. From baño.
Indo-European
Romance
Asturian bañar, Portuguese banhar, Galician bañar, Catalan banyar, French baigner
banco (Noun) (finance) "bank"
13th cent. From French banque 'id.,' from Italian banca "moneychanger's table," from Old Italian banca "bench." From a West Germanic language, probably Lombardic *bank (compare Old Saxon bank "bench," Old High German banc 'id.'). From Proto-Germanic *banki- 'id.' Of unknown origin. Possibly a substrate word.
Indo-European
Romance
Asturian bancu, Portuguese banco, Galician banco, Catalan banc, French banque, Romanian banca
Germanic
Old Norse bekkr, Old High German banc, English bench