Uncertain. Perhaps: * From Proto-Indo-European *sekʷ- (“to follow”), the same root of sequor. Properly, following, later in rank or order, i. e. less than something mentioned before. * Others refer it to Proto-Indo-European *swe- + *-ḱʷo-.
Practica hablar y memorizar " secus " y muchas otras palabras y oraciones en latín .