Thats not an emoji.
> There is also the \(°O°)\, indicating a hooligan or crazed behaviour, and the (ﾉ◕ヮ◕)ﾉ*:･ﾟ.
Of course, one could argue that since the word is now being used internationally, it's not necessary for them to be interpret in the same way as its roots.
Emoticons predate Unicode and emoji, but were later adapted to include Unicode characters.
Multi-character ones would be called smileys, emotes, or emoticons. The confusion comes from the fact that many messengers will automatically replace multi-character emotes with an emoji.
Emoji is a Japanese loan word 絵文字 (literally picture character), you can read more about them:
https://en.wikipedia.org/wiki/Emoji
Emoji in English can used as a singular or plural word but you can also write emojis.
Emoticons are then usually made up out of multiple ASCII-symbols, although general Unicode is by now also in use: :), :-), :|, :[ ...
And then for the "ㄟ(ツ)ㄏ"-Emoticon, you can get more specific about it and call it "Kaomoji". Kaomoji are not Emoji, even though the two sound related, and are actually a more horizontal style of Emoticons, so basically any Emoticon which you can read without turning your head: ㄟ(ツ)ㄏ, ^^, (っ´▽`)っ, (╯°□°)╯︵ ┻━┻, ఠ_ఠ ...