Final answer:
The castrato was a castrated adult male soprano popular in the Baroque era.
Step-by-step explanation:
The castrated male soprano popular in the Baroque era is known as a castrato. Castrati were adult males who were castrated before puberty in order to preserve their high voices. They were highly sought after for their vocal abilities and were often featured in opera performances. Examples of famous castrati from the Baroque era include Farinelli, Senesino, and Caffarelli.