Meaning

noun spectators at a golf or tennis match

noun a porch along the outside of a building (sometimes partly enclosed)

noun a room or series of rooms where works of art are exhibited

originFrom Middle English galery, gallerye, from Middle French galerie, gallerie, from Old French galerie, gallerie (“a long portico, a gallery”), from Medieval Latin galeria (“gallery”), of unknown origin. Perhaps an alteration of Latin galilea (“church porch”), probably from Latin Galilaea, Galilee, region of Israel. More at Galilee.

Etymology from Wiktionary, CC BY-SA 3.0