N3 — outside your level filter
あるいは
あるいはaruiwaN3formal
or; alternatively — and, standing before a whole sentence, "possibly"
ご質問は電話、あるいはメールでお寄せください。
go shitsumon wa denwa, aruiwa meeru de oyose kudasai.
Please send your questions by telephone or by e-mail. formal
あの様子では、あるいは彼はもう知っているのかもしれない。
ano yousu de wa, aruiwa kare wa mou shitte iru no kamo shirenai.
Judging by how he looked, it may well be that he already knows. neutral
All examples4
or; alternatively — two candidates sit side by side, either may hold
ご質問は電話、あるいはメールでお寄せください。
go shitsumon wa denwa, aruiwa meeru de oyose kudasai.
Please send your questions by telephone or by e-mail. formal
この問題は法律の面から、あるいは経済の面から論じることができる。
kono mondai wa houritsu no men kara, aruiwa keizai no men kara ronjiru koto ga dekiru.
This problem can be discussed from a legal angle, or alternatively from an economic one. neutral
possibly; it may even be that — puts forward one live possibility
あの様子では、あるいは彼はもう知っているのかもしれない。
ano yousu de wa, aruiwa kare wa mou shitte iru no kamo shirenai.
Judging by how he looked, it may well be that he already knows. neutral
交渉は難しいが、あるいは来月中にまとまるだろう。
koushou wa muzukashii ga, aruiwa raigetsu chuu ni matomaru darou.
The negotiations are difficult, but they may possibly come together within next month. neutral
How it's formed2
Notes
sets up the guess and something at the end of the sentence has to complete it.