The only free and comprehensive online etymological dictionary of the Spanish language
según (Preposition) "according to"
13th cent. Apocopation of an unattested pre-form *segundo. From Latin secundum 'id.' From secundum "after," from secundus "second," "following" (see segundo (1)).
segunda f. (Noun) "double turn of a lock;" (singular & plural) "double meaning"
From segundo (1).
segundo (1) m. (Adjective, Noun) "second"
13th cent. Old Spanish segundo, rarely secundo; apocopated form segund, segunt. From Latin secundus 'id.' From Proto-Italic *sekwo-ndo- "second," but literally "the following." See seguir.
Indo-European
Romance
Portuguese segundo, Catalan segon, French second, Italian secondo, Romanian secund
segundo (2) m. (Noun) (time) "second"
From Latin secundus "second (in time)" but originally the numeral "second." The sense development from a number to an increment of time derives as a metaphor from the Latin idea of an hour as composed of two parts: the second and the minute. The pars minuta prima "the first small part" was the minute and the pars minuta secunda "the second small part" was the second. For a continued etymology of the word secundus, see segundo (1).
seguramente (Adjective) "surely," "securely"
From seguro and -mente, an adjective-forming suffix.
seguridad f. (Noun) "security"
13th cent. From Latin securitatem, accusative of seguritas 'id.,' from securus "careless," "serene" (see seguro).
seguro m. (Adjective, Noun) "secure;" "insurance"
Early 13th cent. From Latin securus "careless," "serene" composed of se- "without" and cura "care." See respective entries for se- and cura for their further etymologies.
Indo-European
Romance
Asturian seguru, Portuguese seguro, Galician seguro, Catalan segur, French sûr, Italian sicuro, Aromanian siguro, Romanian sigur, Sardinian securu
seis (Cardinal Number) "six"
12th cent. Old Spanish seis, uncommon seyes (probably under analogy from leyes). From Latin sex 'id.' From Proto-Italic *seks 'id.' From Proto-Indo-European *u̯ek-s 'id.'
Indo-European
Romance
Asturian seis, Portuguese seis, Galician seis, Catalan sis, French six, Italian sei, Aromanian shasi, Romanian șase, Sardinian ses
Celtic
Celtiberian sues "six," meaning uncertain, Old Irish 'id.,' Middle Welsh chwech 'id.,' Old Breton hue 'id.,' Cornish whegh 'id.'
Germanic
Gothic saihs "six," Old Norse sex 'id.,' Old High German sehs 'id.,' Old Saxon sehs 'id.,' English six
Albanian
Albanian gjashtë "six"
Balto-Slavic
Old Church Slavonic šestь "six," Russian šest' 'id.,' Czech šest 'id.,' Polish sześć 'id.,' Slovene šę̑st 'id.,' Lithuanian šešì 'id.,' Latvian seši 'id.'
Hellenic
Ancient Greek ἕξ (héks) "six," Doric ϝέξ (wéks) 'id.'
Armenian
Armenian vec' "six"
Indo-Iranian
Sanskrit ṣáṣ- "six," Young Avestan xšuuaš 'id.'
semana (1) f. (Noun) "week"
12th cent. Old Spanish setmana. From Latin septimana "week" (but more literally "of the seventh"), from septimus "seventh" (see séptimo) and the adjective-forming suffix -anus (see -ano).
Indo-European
Romance
Asturian sermana, Portuguese semana, Galician semana, Catalan setmana, French semaine, Italian settimana, Aromanian siptãmãnã, Romanian săptămână
Semana (2) (Surname)
According to Tibón (1988), the last name Semana is from Arabic sammana "butter vender" (compare samn "butter).
Afro-Asiatic
Semitic
Akkadian šamnu(m) "oil," "fat," Ugaritic šmn "oil," "fat," Ancient Hebrew šemen "oil," Punic šmn 'id.'