Possibly from an Afro-Portuguese variant ofPortuguesesenhor, reduced to*siô, with nasalization taking place by analogy ofnhum.[1]Doublet ofnhum, via an older formnhom.
^Batalha, Graciete Nogueira (1988) “sium”, inGlossário do dialecto macaense: notas linguísticas, etnográficas e folclóricas [Glossary of the Macanese dialect: linguistic, ethnographic and folkloric notes], Macau:Instituto Cultural de Macau,page270