The only free and comprehensive online etymological dictionary of the Spanish language
caballero m. (Noun, Adjective) "gentleman," "cowboy," "knight;" "gentlemanly"
11th cent. From Late Latin caballarius "horseman," from Latin caballus "horse" (whence caballo) and -arius, an agent-forming suffix (see -ero).
Also the origin of the surnames Caballero, Caballeros.
Indo-European
Romance
Asturian caballeru, Portuguese cavaleiro, Galician cabaleiro, Catalan cavaller, French chevalier, Italian cavaliere, Romanian cavaler, Sardinian cabaglieri
caballo (Noun) "horse"
10th cent. From Latin caballus 'id.' Of non-Indo-European origin. Borrowed from an unknown language in Asia with the root *kab- (compare Turkish käväl "horse;" Russian kobýla "mare;" Old Church Slavonic koņь "horse"). Further consider Semitic words for camel with a structure *gam- (Hebrew gāmāl), hypothesized to be borrowed from an unattested Sumerian word.
Also the origin of the surnames Caballero, Caballeros, first given to horsemongers.
Indo-European
Romance
Asturian caballu, Portuguese cavalo, Galician cabalo, Catalan cavall, French cheval, Italian cavallo, Aromanian cal, Romanian cal, Sardinian cadhu
Hellenic
Ancient Greek καβάλλιον (kabállion) "workhorse"
cabello m. (Noun) "hair"
11th cent. From Latin capilla 'id.' Of unknown origin. Possibly from a non-Indo-European language with a root *kap- (see cabo).
Also the origin of the surname Cabellos.
Indo-European
Romance
Asturian cabellu, Portuguese cabelo, Galician cabelo, Catalan cabell, French cheveu, Italian capello
caber (Verb) "to fit"
12th cent. From Latin capere "to take in," "to capture." From Proto-Italic *kap-i- 'id.' Of unknown origin.
Indo-European
Romance
Asturian caber, Portuguese caber, Galician caber, Catalan cabre
Germanic
Gothic haban "to have," Old Norse hafa 'id.,' Old High German habēn 'id.,' Old Saxon hebbian, Old English habban (English to have)
Albanian
kap "to seize"
Balto-Slavic
Latvian kàmpt "to obtain"
cabeza f. (Noun) "head"
10th cent. From Vulgar Latin *capitia 'id.,' from caput "head" (see cabo) and -itia, an abstract noun-forming suffix (see -eza).
Also the origin of the surname Cabezas, first applied as a nickname to local leaders known for their intelligence.
Indo-European
Romance
Asturian cabeza, Portuguese cabeça, Galician cabeza, Catalan cabeç, French chevet, Italian cavezza
Western Vulgar Latin reanalyzed the neuter plural as a feminine singular noun (see arma and hoja).
cabezo m. (Noun) "mountain peak"
14th cent. From Latin capitium 'id.' From caput "head" (see cabo).
Indo-European
Romance
Asturian cabezu, Portuguese cabeço, Galician cabezo
cabo m. (Noun) "cape"
10th cent. Vulgar Latin caput, recorded in the Appendix Probi of the 3rd or 4th cent. In Vulgar Latin caput may have meant the end as well as the beginning, as seen in Italian far capo "to commence." From Latin caput "head." From Proto-Italic *kaput 'id.' From an unknown pre-Indo-European substrate language *kap- "cup."
Indo-European
Romance
Asturian cabu, Portuguese cabo, Galician cabo, Catalan cap, French chef, Italian capo, Aromanian cap, Romanian cap, Sardinian kabu
Celtic
Old Irish cúäch "cup," Middle Welsh cawg 'id.'
Germanic
Gothic haubiþ, Old Norse hǫfuþ, Old High German haubit, Old Frisian hāved, Old English hāved (English head)
According to Beekes (1996), there are five reasons why the word is borrowed from another language. First, cognates in other languages point to *a in Proto-Indo-European - a vowel which did not exist. Second, if one reconstructs *kh2p- we must account for a missing full-grade **keh2p-. Third, an incongruous a/au variation (Old English hafut versus Gothic haubiþ) cannot be satisfactorily explained by contamination and there is no reason to assume an ablaut that ended in a stop. Fourth, the suffix -ut in Latin caput is utterly alien to Italic tongues except as the perfect participle, which makes little sense. Admittedly it could be a borrowing from Celtic, but that does nothing to explain the suffix *-it in Germanic, as evidenced in Gothic haubiþ. The most parsimonious explanation is that suffixes *-ut and *-it are remnants from a non-Indo-European language. Fifth and finally, k-initial plain velars words are rare in Proto-Indo-European. Their presence should raise suspicion. On the other hand, Kroonen (2014) believes the words are of native Indo-European stock, as he assumed variation in *a/au was due to supplanting the old proterodynamic paradigm with -au- (borrowed from the oblique).
"Given this situation [above] - which has always been clear - it seems certain the word is a loan. I find it surprising that I nowhere have seen even the suggestion that the word could be non-IE." ~ R. Beekes, "Ancient European Loanwords" (1996)
cabrón m. (Noun) (vulgar) "motherfucker;" "he-goat"
13th cent. From capra and augmentive suffix -ón.
Indo-European
Romance
Asturian cabrón "motherfucker," "cuckold," Portuguese cabrão "billygoat," "cuckold," Galician cabo, Catalan cap, French chef, Italian cabrone "billygoat"
cacho (1) m. (Noun) "piece," "slice," "chunk"
Very late 15th cent. Originally meaning a pottery sherd. From Vulgar Latin *cacculus "pot," from Late Latin caccubus 'id.' Borrowed from Ancient Greek κάκκαβος 'id.' Of unknown origin, however compare Akkadian kukkubbu, kukkupu "rhyton," "pig's stomach" - if such a similarity is due to anything more than coincidence, we may posit an origin in a Semitic source.
Indo-European
Romance
Asturian cachu, Portuguese caco, Galician cacho
cacho (2) m. (Noun) "surmullet"
From Vulgar Latin *cattulus "puppy," from Latin catulus "animal young." From Proto-Italic *kat-elo- 'id.' Of uncertain origin, unlikely to be from Proto-Indo-European.
Indo-European
Romance
Portuguese cátulo
Italic
Umbrian katel "sacrificial animal"
Germanic
Old Icelandic haðna "kid," Middle High German hatele "goat"
Balto-Slavic
Czech kót "breeding period," Polish kot (defined by Derkson (2015) as "place where forest animals young"), BCS kȏt "breeding period," Slovene kòt "brood"