what is a sound barrier
Definition of SOUND BARRIER. : a sudden large increase in aerodynamic drag that occurs as the speed of an aircraft approaches the speed of sound.See sound barrier defined for English-language learners.See sound barrier defined for kids. ADVERTISEMENT. a sudden large increase in aerodynamic drag that occurs as the speed of an aircraft approaches the speed of sound. See sound barrier defined for English-language learners. See sound barrier defined for kids.