あるいは

About

あるいは is formal in tone and is most commonly found in written Japanese.

あるいは's main use is to present alternatives, and has two distinct usages: ① "X, or Y" (where it acts as a conjunction) and ② "Perhaps/maybe" (where it acts as an adverb).

①
E.g. 言語学げんごがく、あるいはそれに関係かんけいする単位たんいが必要ひつようです。 "Linguistics (credits), or related credits are required."

②
E.g. あるいは、それは本当ほんとうのことなのかもしれない。 "Perhaps that's the truth."

For usage ①, あるいは likes to follow options that are presented using the か particle.

E.g. その日ひのレッスンを欠席けっせきか、あるいは変更へんこうしたいのですが可能かのうですか。 "I would like to either miss or modify that day's lesson, but is this a possibility?"

For usage ②, あるいは generally comes at the start of a sentence, and when it comes in the middle, is not required to follow a ～か option.

E.g. 日本にほん独特どくとくのものと考かんがえていたが、あるいは、これは世界せかい共通きょうつうの考かんがえ方かたなのかもしれない。 "I had thought that this was something unique to Japan, but perhaps it's a common way of thinking worldwide."

Summary

• 

  あるいは is formal in tone

• 

  あるいは's main use is to present alternatives, and has two distinct usages: ① "X, or Y" (where it acts as a conjunction) and ② "Perhaps/maybe" (where it acts as an adverb)

• 

  For usage ①, あるいは likes to follow options that are presented using the か particle

• 

  For usage ②, あるいは generally comes at the start of a sentence, and when it comes in the middle, is not required to follow a ～か option