Flat as a Board

In anime, "flat as a board" is a rude way to describe flat-chested characters, who have "small breasts"," hin'nyuu 貧乳.

This everybody knows. What you may not know is that there are two different terms for this in Japanese, depending on the sort of board.

• Cutting Board
• Washboard

Cutting Board

First, we have a manaita まな板, "cutting board."

Character: Mile マイル
Anime: Watashi, Nouryoku wa Heikinchi de tte Itta yo ne! 私、能力は平均値でって言ったよね！ (Episode 2)

This is a terribly flat board used to chop vegetables, meat, for cooking.

Washboard

Second, we have sentakuita 洗濯板, "washboard," a "board," ita 板, for doing "laundry," sentaku 洗濯.

Anime: Dungeon ni Deai wo Motomeru no wa Machigatteiru Darou ka ダンジョンに出会いを求めるのは間違っているだろうか (Episode 2)

• Note: the washboard is at left. The thing at the right side is called a "cow," which is the opposite of what this article is a about.

This is the sort of board used to wash clothes. If you are a current year person accustomed to the wonders of technology and washing machines such that you don't know how this ancient laundry wooden instrument is supposed used, perhaps this will explain:

Character: Senko-san 仙狐さん
Anime: Sewayaki Kitsune no Senko-san 世話やきキツネの仙狐さん (Episode 2)

As you can see above, while a manaita is perfectly flat, a sentakuita has ridges as part of its design. These ridges are there so you can rub the clothing against them and with that remove whatever filth is staining the clothes. It's not much, but it's better than doing it using just your hands.

Now, as far as flat-chested characters, and,well, people, also, are concerned, there's actually supposed to be a difference between calling someone a cutting board, manaita, and calling someone a washboard, sentakuita.

The word sentakuita used as a slang for flat-chest also implies that you can see the girl's ribs through her chest, like under her collarbone. That's because a washboard has ridges, and the rib-cage is supposed to be those ridges.

• abara ga uku
  あばらが浮く
  The ribs appear from underneath.
  • uku
    浮く
    To come from the bottom toward the surface.
    To float. (in water, in the air.)

In other words, manaita まな板 means simply flat-chested, while sentakuita 洗濯板 means flat-chested and skinny.

• The size of a woman's breasts is defined mostly by the amount of fat stored inside the breasts.
  • The fat in breasts, thighs, and buttocks is called gynoid fat, and its distribution is controlled primarily by the estrogen hormone. Two women with the same fat amount won't necessarily have the same breast size.
• Someone with low body fat naturally has smaller breasts, since the body will have nothing to fill those breasts with.
• They'll also have less fatty tissue between the skin and bones, which means the shape of the bones becomes more noticeable.
• Hence the connection between being flat-chested and being skinny enough that the rib bones are visible.

Despite all this, in practice, sentakuita is used even when that's not the case. It's used more commonly than manaita, even though I can't seem to find a single female character that matches what it's supposed to mean.

There are many skinny characters that would probably fit the description if they were real-life people, but as drawings in anime, where more details means a lot more work, artists won't bother drawing washboard ridges on bony chests unless the character is emaciated.