一千(いっせん)

いっせん
number
one thousand (explicit form)
formalnumberquantity
1. one thousand (explicit form)
The number 1,000 with 一(いち) stated. Where plain 千(せん) suffices in ordinary counting, 一千(いっせん) is used in formal writing and, above all, inside larger figures such as 一千万(いっせんまん) (10,000,000).
一千万(いっせんまん)円(えん)。
Ten million yen.
被害額(ひがいがく)は一千(いっせん)億(おく)円(えん)に達(たっ)した。
The damages reached one hundred billion yen.
一千(いっせん)年(ねん)以上(いじょう)前(まえ)に書(か)かれたこの作品(さくひん)は、今(いま)も読(よ)み継(つ)がれている。
This work, written more than a thousand years ago, is still read today.

一(いち) shortens to いっ before 千(せん). Unlike 一万(いちまん), where the 一(いち) is obligatory, the 一(いち) in 一千(いっせん) is optional — plain 千(せん) is the default in speech and everyday writing.

WHEN 一千(いっせん) IS PREFERRED:

  • Inside larger figures: 一千万(いっせんまん) (10,000,000), 一千(いっせん)億(おく) (100,000,000,000)
  • Formal and journalistic writing, where the 一(いち) makes the magnitude unmistakable
  • Rhetorical spans of time: 一千(いっせん)年(ねん) (a thousand years)

Similar words

Related Words

Compare: 千円(せんえん) (one thousand yen)
general
Added 2026.8.7 9:23 · Revised 2026.9.2 13:02
30000/30472_issen