How to say "extension" in Japanese

• 延長えんちょうJLPT N2approx.Common
  noun, suru verb, transitive verb, intransitive verbCovers extension as prolongation or lengthening: making something longer in time or distance, such as extending a period, a stay, or a line. It is not for enlarging size or scope.
  宿泊しゅくはくをもう一いち晩ばん延長えんちょうできますか。↗

  Can I extend my stay one more night?
• 拡大かくだいJLPT N3approx.Common
  noun, suru verb, transitive verb, intransitive verbExtension in the sense of expansion: making something larger in size, scale, or scope, as with enlarging a picture or expanding a business. It does not concern physical length.
  今年ことしは事業じぎょうが５０％拡大かくだいした。↗

  The business has expanded by 50% this year.
• 拡張かくちょうJLPT N2approx.Common
  noun, suru verb, transitive verbAlso extension as expansion or enlargement, overlapping closely with 拡大; it leans toward extending scope, range, or capacity — extending what something covers or can do — rather than simple magnification.
  学校がっこうの体育館たいいくかんが拡張かくちょうされた。↗

  The school gymnasium was enlarged.
• 猶予ゆうよCommon
  noun, suru verb, transitive verb, intransitive verbExtension only in the temporal sense of postponement or deferment: being granted extra time before a deadline or obligation. It never covers spatial length or enlargement of scope.
  事態じたいは一刻いっこくの猶予ゆうよも許ゆるさない。↗

  There's not a moment to waste.
• 波及はきゅうCommon
  noun, suru verb, intransitive verbMarginal as a rendering of extension: it really means spread, influence or effects reaching outward into other areas, as in ripple effects. Choose it only when extension implies spreading influence.

Use 延長 for lengthening in time or distance, 拡大 and 拡張 for expansion of size, scope, or capacity, 猶予 only for extra time before a deadline, and 波及 only for spreading influence or effects.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

• 延長えんちょうextension
• 拡大かくだいexpansion
• 拡張かくちょうexpansion
• 猶予ゆうよpostponement
• 波及はきゅうspread
• エクステンションextension
• 引き延ばしひきのばしextension
• 別館べっかんannex (to a building)
• 伸長しんちょうexpansion
• 更改こうかいrenewal
• モラトリアムmoratorium
• 発展はってんdevelopment
• 増設ぞうせつadding (equipment, facilities, etc.)
• 延伸えんしんstretching
• 外延がいえんextension
• 拡張部分かくちょうぶぶんextension
• 伸展しんてんexpansion
• 継ぎ足しつぎたしaddition
• 展延てんえんspreading out
• 子機こき(telephone) extension
• 機能拡張きのうかくちょう(software) extension
• ひらきextension
• のびelongation