The only free and comprehensive online etymological dictionary of the Spanish language
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