Main Entry: ¹ul·tra·sound

Pronunciation: \ˈəl-trə-ˌsau̇nd\

Function: noun

1 : vibrations of the same physical nature as sound but with frequencies above the range of human hearing—compare infrasound
2 : the diagnostic or therapeutic use of ultrasound and especially a noninvasive technique involving the formation of a two-dimensional image used for the examination and measurement of internal body structures and the detection of bodily abnormalities—called also echography, sonography, ultrasonography
3 : a diagnostic examination using ultrasound