Galileo Galilei

American Heritage® Dictionary of the English Language, Fourth Edition

1. Galileo Galilei 1564-1642. Italian astronomer and physicist. The first to use a telescope to study the stars (1610), he was an outspoken advocate of Copernicus's theory that the sun forms the center of the universe, which led to his persecution and imprisonment by the Inquisition (1633).

WordNet 3.0

1. n. Italian astronomer and mathematician who was the first to use a telescope to study the stars; demonstrated that different weights descend at the same rate; perfected the refracting telescope that enabled him to make many discoveries (1564-1642)