a large system of stars, stellar remnants, interstellar gas, dust, and dark matter bound together by gravity (e.g., the Milky Way is a galaxy containing billions of stars).

多数の恒星、恒星残骸、星間ガス、塵、暗黒物質が重力で結びついた大規模な天体系（例：天の川銀河は何十億もの恒星を含む銀河）

specifically, the Milky Way when 'the Galaxy' is used as a proper noun referring to the galaxy that contains our solar system.

特に、私たちの太陽系を含む銀河を指す固有名詞としての「銀河（天の川）」

a figurative use meaning a large number or collection of impressive people or things (e.g., 'a galaxy of stars' meaning many outstanding individuals).

比喩的表現で、多くの優れた人物や注目すべき物事の集合（例：「a galaxy of stars」＝多くの著名人・優れた人々）