From Greek Kynthia, an epithet applied to the goddess Artemis, who was supposed to have been born on Mount Kynthos on the island of Delos. The mountain name is of pre-Greek origin. Cynthia was later used by the Roman poet Propertius as the name of the woman to whom he addressed his love poetry. The English given name was not used in the Middle Ages, but dates from the classical revival of the 17th and 18th centuries.
German: 1. habitational name from any of several places so named in northern Germany. 2. metonymic occupational name for a barber or nickname for someone who wore a conspicuous tassel or feather, from Middle Low German, Middle High German quast(e) ‘tuft’, ‘tassel’, ‘brush’, also ‘fool’.