彗星（すいせい、suiseい）
- comet

The Japanese word 彗星 (すいせい) refers to a comet. A comet is a celestial object consisting of a nucleus of ice and dust and, when near the sun, a "coma" (a hazy envelope) and a tail. These tails are produced by the solar wind and radiation.

⚫︎その彗星は夜空を横切った。 Translation: That comet streaked across the night sky. ⚫︎彗星の出現を観測した。 Translation: I observed the appearance of a comet.

The word 彗星 is used in formal and informal contexts to describe a comet. You might use it in a conversation about astronomy, the news, or even science fiction.

⚫︎The word is primarily written in kanji as 彗星. ⚫︎The reading is すいせい in hiragana. ⚫︎It is not typically written in katakana except for emphasis or to represent a foreign word. ⚫︎There are no variations in okurigana.

There are no direct synonyms in Japanese that specifically mean "comet". However, related terms include: ⚫︎ほうき星 (ほうきぼし) - "broom star", an old term for a comet, though less commonly used today.

There aren't specific antonyms for 彗星. It's a specific term for a celestial object.

最近、彗星に関する新しい研究が出版された。 ・Translation: Recently, new research on comets was published. ・Explanation: This sentence describes the publication of recent studies related to comets.

あの彗星は数年後にまた見えるだろう。 ・Translation: We'll be able to see that comet again in a few years. ・Explanation: This sentence describes the periodic nature of comets and when it can be seen.

The word 彗星 is a compound word. 彗 (すい) means "broom" or "a broom-like object," referring to the comet's tail. 星 (せい) means "star" or "celestial body." Therefore, 彗星 literally translates to "broom star," reflecting the appearance of the comet.