sub- — under, below, lower, secondary (affix)

subway A1

/ˈsʌbˌweɪ/ An underground railway used to move people around a city. M S

submarine B1

/sʌb.məˈɹin/ A ship that can travel under the surface of the water. M S

subtitle B2

/ˈsʌbtaɪtəl/ Words shown on screen that translate or write out the dialogue in a film or show. M S

subzero B1

/ˌsʌbˈzɪr.oʊ/ below zero on a numerical scale, especially a temperature scale M S

submerge C2+

/səbˈmɜrdʒ/ to put or sink below the surface of a liquid M S