[ gal-uh-ley-oh, -lee-oh; for 1 also Italian gah-lee-le-aw ]
/ ˌgæl əˈleɪ oʊ, -ˈli oʊ; for 1 also Italian ˌgɑ liˈlɛ ɔ /


Galileo Galilei, 1564–1642, Italian physicist and astronomer.
Aerospace. a U.S. space probe designed to take photographs and obtain other scientific information while orbiting the planet Jupiter. Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

British Dictionary definitions for galileo galilei (1 of 2)


/ (ˌɡælɪˈleɪəʊ) /


full name Galileo Galilei. 1564–1642, Italian mathematician, astronomer, and physicist. He discovered the isochronism of the pendulum and demonstrated that falling bodies of different weights descend at the same rate. He perfected the refracting telescope, which led to his discovery of Jupiter's satellites, sunspots, and craters on the Earth's moon. He was forced by the Inquisition to recant his support of the Copernican system

British Dictionary definitions for galileo galilei (2 of 2)


/ (ˌɡælɪˈleɪəʊ) /


a US spacecraft, launched 1989, that entered orbit around Jupiter in late 1995 to study the planet and its major satellites; burned up in the planet's atmosphere in 2003
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Science definitions for galileo galilei

Galileo Galilei

[ găl′ə-lāō găl′ə-lā ]

Italian astronomer, mathematician, and physicist. He was the first to use a telescope to study the stars and planets, and he discovered various astronomical phenomena and physical principles.


Galileo Galilei is considered to be the father of modern experimental science. His most significant experiments concerned gravitation. Galileo conducted a series of experiments to measure the effects of gravity on motion, such as measuring the speed of balls of different weights rolling down inclined planes. He found that all objects accelerate at the same, constant rate. He is also famous for the probably apocryphal experiment in which he dropped balls of different masses from the Tower of Pisa. Had the experiment actually taken place, air resistance might have caused the balls to fall at different rates, defying the principle of acceleration that Galileo was trying to demonstrate. In 1609, having heard of the invention of the spyglass, a tube with a piece of glass at each end that made objects appear closer and larger, Galileo set about making his own. Using his telescope, he observed mountains on the Moon's surface (which was thought to be flat), Jupiter's four largest moons, and sunspots. Because he openly supported Copernicus's theory that Earth and all the planets orbit the Sun, Galileo was called before authorities of the Catholic Church and forced to declare the theory false. He was put under house arrest on his own farm, where he continued his scientific work until the end of his life.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

Culture definitions for galileo galilei


[ (gal-uh-lee-oh, gal-uh-lay-oh) ]

An Italian scientist of the late sixteenth and early seventeenth centuries; his full name was Galileo Galilei. Galileo proved that objects with different masses fall at the same velocity. One of the first persons to use a telescope to examine objects in the sky, he saw the moons of Jupiter, the mountains on the moon, and sunspots.


Authorities of the Roman Catholic Church forced Galileo to renounce his belief in the model of the solar system proposed by Nicolaus Copernicus. Galileo had to assert that the Earth stands still, and the sun revolves around it. A famous legend holds that Galileo, after making this public declaration about a motionless Earth, muttered, “Nevertheless, it does move.”
The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.