Doppler ultrasound is a type of ultrasound that depends on the Doppler Effect, a change in the wave's frequency, which can occur from the motion of a reflector, such a red blood cell. We experience the Doppler Effect when, for example, an ambulance approaches us, passes and then drives away.
Definition of PLACODERM. : any of a class (Placodermi) of extinct chiefly Devonian fishes with an armor of bony plates and primitive jaw structures.ADVERTISEMENT. New Latin Placodermi, ultimately from GK plak-, plax + derma skin â more at derm-. any of a class (Placodermi) of extinct chiefly Devonian fishes with an armor of bony plates and primitive jaw structures. ADVERTISEMENT.
Definition of PLACODERMI. : a class of extinct fishes with an armor of large bony plates and primitive jaw structures that has been taken as equivalent to Antiarcha plus Arthrodira but is now usually extended to include also the Acanthodii, Cycliae, and minor groups â compare chondrichthyes.â placÂ·oÂ·derÂ·moid adjective.ADVERTISEMENT.rigin of PLACODERMI. New Latin, from plac- + Greek derma skin â more at derm-. This word doesn't usually appear in our free dictionary, but the definition from our premium Unabridged Dictionary is offered here on a limited basis. Note that some information is displayed differently in the Unabridged.