TLDR: Older Brother

A little more detail if you like-
Onii can end with 3 different Japanese honourifics, -San, -Chan, or -Sama.
-San is the basic ending for the basic big bro.
-Chan is a more compassionate ending for Onii if you really love your big brother and feel emotionally attached to him greatly
-Sama is a bit of a formal ending for big brother, nothing too special.
My Onii-San is a cool bro
I really love my Onii-Chan!
Yes he is my Onii-Sama
by Rywen March 10, 2015
Onii-Chan means "Big brother" in Japanese. Most people assume it's a mating call of some sort because of hentai but no that's just hentai. Lots of hentai has incest.
"Onii-chan! Drive me to my friend's house!"
by RigsSaysGoodbye February 3, 2018
1. Used to refer to your older brother in a cute way (in japanese).
2. In hentai, mostly lolicon, the lolis use it to refer in a cute way to their lover.
3. Cringey term that lots of weeaboos use to refer to their crushes.
1. Onii-chan, watashitachiha shukudai o shinakareba narimasen. (Onii-chan, we have to do our homework.)
2. Onii-chan, daisuki! (I love you, onii-chan!)
3. Len onii-chan is so cute! He's my shota! Kawaii!
by Monokuma...pupupupu! September 28, 2020
Brother in Japanese. Used mostly by little girls or children. PLEASE do not make this sexual its gross.
"Welcome home, onii-chan! Dinner is one the table!"
by Dekus_hair_23 October 5, 2021
The japanese of big brother (or just brother). And please dont say this to japanese ppl unless theyre your brother.
Girl: Onii-chan, can you please be sweet and pass me my plush?
Boy (a.k.a Onii-chan): Sure, here.
by N3K0-! July 8, 2021
Means big brother in japanese and not used in any type of sexual or romantic way. It just means big brother in japanese.....chan here refers to the formal greeting that any kind of people use it to refer it to the elders where onii means big so in total it refers to big elder or big brother.
Onii chan is working in a big place nowadays.
by August 22, 2022