A person who sings a descant or performs descant parts in music; someone who speaks at length about a topic.
From 'descant' + '-er' suffix denoting an agent or person. The musical sense developed in medieval England among church singers; the speaking sense evolved from the discourse metaphor.
In Renaissance choirs, the descanter was the special vocalist who could handle the tricky high melody—similar to how a lead guitarist in a band has to be technically skilled to play the flashy parts.
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