Mass transfer refers to the movement of mass between two phases, such as gas and liquid, or between different parts of the same phase. There are many synonyms for mass transfer, including diffusion, convection, advection, dispersion, and migration. These terms describe different types of mass transfer processes, with diffusion referring to the movement of mass due to concentration gradients, convection referring to movement due to fluid flow, advection referring to the movement of mass by a fluid, dispersion referring to the random movement of particles, and migration referring to the movement of charged particles in an electric field. Understanding these synonyms is important for scientists and engineers working in fields such as chemical engineering, materials science, and environmental science.