Moeblob

In anime, a moeblob means a character that is extremely cute, moe 萌え, and that's it. They have no other qualities, no other defining features, hence why they're just an indiscernible "blob" of moe.

This is a western anime slang normally used in criticism against such characters.

• Meaning
  
  • Not a Genre
  • Not Drawn Blobby
  • In Japanese

Meaning

In essence, a moeblob character is cute for the sake of being a cute character. They do nothing more than looking adorable and talking adorably, to the point it feels extremely forced and out-of-place to an audience not into that sort of character.

Furthermore, since moe often attempts to make characters cuter by trying to make them look and behave more like children, character who are extreme moeblobs end up being high school girls that look like they're in grade school and behave like they're infants.

I'm not joking.

A layman would definitely think some moeblobs are supposed to be mentally challenged characters, or that they're high on drugs. They often talk slow and dizzy. They're silly constantly. They love hugging people out of nowhere.

• sukinshippu
  スキンシップ
  "Skinship." (wasei-eigo 和製英語)
  A Japanese term for making a relationship more intimate through physical skin-on-skin contact.

Even in the anime fandom, it's not unusual for forums to be filled with questions like "does (moeblob character) have autism?" Well, to be fair, it's more like "is (moeblob character) mentally retarded?"

Offensive remarks aside, it's clear that these characters are aggressively stupid just because the author thinks stupid equals cute. Their design as the stupid-cute character deprives them from being or becoming anything better than that, hence why moeblobs are despised by its critics.

Note that, in practice, moeblobs character do in fact have things you could call features, like moe attributes. For example, you can have a moeblob that's also a "rich girl," ojousama お嬢様, character.

Not a Genre

The term moeblob DOES NOT refer to a genre. Some people mistakenly use the term moeblob to refer to anime that have a bunch of moeblob characters, but such anime are already classifiable by other genres. For example:

• iyashi-kei
  癒し系
  "Healing-type." A series, character, or person capable of healing stress. An anime genre that's soothing, avoiding eliciting strong emotions.
• nichijou-kei
  日常系
  "Daily-type." SoL. Slice of Life. Any anime that focuses characters in their trivial, day-to-day activities, like waking up, going to school or to work, and coming back home. Tends to be episodic and avoid major plot developments.
• CGDCT
  Cute Girls Doing Cute Things. Any anime where the main cast is composed entirely of girls. Not to be confused with the inferior genre, harem, which has a male protagonist nobody wants.

The combination of the three genres above consistently results in the most moeblob-infested anime ever, as such anime would be full of girls, wouldn't have any interesting plot developments, and would be design to be cute and soothing. Examples include:

• Keion!
  けいおん！
  K-On!
• Non Non Biyori
  のんのんびより
• Gochuumon wa Usagi Desu ka?
  ご注文はうさぎですか？
  Is [Your] Order a Rabbit?
• Yuyushiki
  ゆゆしき

Not Drawn Blobby

For the record: moeblob DOES NOT mean to be drawn like a blob. Sometimes people post characters literally drawn as blobby accompanied by the word moeblob, but that has nothing to do with the term.

Character: Kotobuki Tsumugi 琴吹紬
Anime: K-On!!, Keion!! けいおん！！ (Season 2) (Episode 14)

To refer to things like this in Japanese:

• deforume
  デフォルメ
  Déformer. (french.)
  Artwork that's drawn distorted, deformed.
  • SD, or Super Déformer, normally means characters drawn in chibi style.
• kaogei
  顔芸
  Face-performance. In anime, normally refers to facial expressions drawn weirdly.

In Japanese

The term moeblob is a western slang with no Japanese equivalent. To begin with, in Japanese moe 萌え doesn't mean simply "cute," but rather an emotion like affection, and can be used toward virtually anything you may like in character designs and anime scenarios in general.

Some related words would be:

• moe-e
  萌え絵
  A moe picture. A drawing drawn for the purpose of eliciting moe.
• moe-kyara
  萌えキャラ
  A moe character.
• moe-goe
  萌え声
  A moe voice.
• moe-anime
  萌えアニメ
  A moe anime.
• moe buta
  萌え豚
  A "moe pig." A type of otaku that loves moe anime.