1. A technique or procedure that is kept hidden or confidential, known only to a select few
The chef guards his secret method for making the perfect sauce.
O chef guarda seu método secreto para fazer o molho perfeito.
2. An undisclosed or proprietary approach to achieving a particular result
The company's secret method of production gives them a competitive advantage.
O método secreto de produção da empresa lhes dá uma vantagem competitiva.