ultrasound

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

:  of, relating to, performed by, using, or specializing in ultrasound <an ultrasound technician> <ultrasound imaging>