I am getting confused when translating from English to Japanese with "-styles" "-types" and "-kinds" of things, methods and equipment.

For sure, I know that "式"(or 方式) is applied to methods of doing something, like measuring, or solving equations. "型" is for structural composition of physical objects. "系" looks like suitable for types of work, like research, manufacturing, financial.

But there are some things in between, like "a device using an A functional component for doing something". So, is it A式(because of its function), A系(because of class of devices based on A), or A型(because A-thing is in the basis of design)?

Are there more or less strict rules for using 系 式 型 ?

1 Answer 1


系 is used to emphasize a product belongs to a certain large "family" or "series". For example, a modern CPU belongs to either ARM系 or x86系. Your smartphone is probably either iPhone系 or Android系. Unsurprisingly, it's relatively rare to coin a new word that ends with 系.

式 and 型 are often interchangeable, but 式 mainly refers to a type of technology/method, whereas 型 vaguely refers to any "type" or "model". You can use 空冷式エンジン and 空冷型エンジン interchangeably ("air-cooled engine"). You can say 人間型ロボット ("humanoid robot") but not 人間式ロボット because 人間 itself is not a type of technology. (年式 as in 1990年式の自動車 is different from 式 explained here. 式 also takes a person/place name, for example 日本式庭園.)

  • Maybe you can also cover non-technology uses like 渋谷系, B型 or 訓令式 Commented Sep 6, 2019 at 2:02
  • So, you guess, 系 is not acceptable in my example, while it is not worldwide used distinguished component. And, probably, 式 fits here better? Yes, like I was afraid, it looks not strict, but easily noticeable by native's eye.
    – Asdf
    Commented Sep 6, 2019 at 3:01
  • 1
    Igor. Yes, what I've seen before, 系 is quite often a non-tech thing, usually a human management related. But not always. And 式 has a connotation of a formula, a systematic thing. But there are shades of gray in between.
    – Asdf
    Commented Sep 6, 2019 at 3:27
  • Seems to relate to the complexity of the technology or system being discussed.
    – Jack Bosma
    Commented Sep 6, 2019 at 12:46

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