The only free and comprehensive online etymological dictionary of the Spanish language
buscar (Verb) "to search for"
12th cent. Unknown origin, perhaps from a hypothetical Vulgar Latin verb *boscare "to search," "to search for kindling" derived from *boscus "woods" (see bosque). Alternatively, Čevelová & Blažek (2009) believe the word was borrowed from Gothic *būska "log of wood."
Asturian buscar "to search," (Palacios del Sil) "to find," Aragonese buscar, Leonese buscare, Portuguese buscar, Galician busca, Italian buscare "to acquire."
Old High German busc, bosc "bush"