Austrian physicist famous for his discovery of the Doppler effect (1803-1853)
"Many scientists cite Christian Doppler as the pioneer who first described how light waves shift in frequency when their source moves."
A Doppler fetal monitor
"The midwife attached the doppler to my belly so we could finally hear the baby's heartbeat clearly."
A surname of German derivation
"The police officer noticed that Officer Doppler was the only one who knew how to navigate the icy roads safely."