agura

In Japanese, agura あぐら means a way to sit on the floor: with your "legs crossed." It's also spelled agura 胡座, and also read as koza 胡坐.

Character: Furuta Sasuke 古田左介
Anime: Hyouge Mono, へうげもの (Episode 2)

Definition

The word agura あぐら is a noun meaning to "sitting legs crossed."^{(デジタル大辞泉)} It's also a suru verb.

agura suru
あぐらする
To sit with legs crossed.
agura wo kaku
あぐらをかく
(same meaning.)
agura wo kumu
あぐらを組む
(same meaning.)

Typically, agura refers to when someone sits on the floor with legs crossed, and contrasts with the seiza 正座, which is when you sit on your knees. In particular, warriors in armor are often depicted sitting in agura position.

Example of characters sitting on the floor, two in seiza 正座 position, on in agura 胡座 position.

Anime: Hyouge Mono へうげもの (Episode 2)

Context: seiza, agura, seiza.

The agura is considered to be a more masculine way to sit compared to the seiza. As typical in Japanese culture, masculine is synonymous with rude, so the proper way to sit formally is the seiza, not the agura.

On the other side, sitting seiza-like but with both legs to one side, called yokozuwari 横座り, "horizontal sitting," or with each legs to one side instead of under you, called W sitting, or wariza 割座, are considered to be more feminine ways to sit.

Shimogamo Yasaburou 下鴨矢三郎, a male tanuki, sitting in agura あぐら with a skirt, while transformed into a sailor outfit-wearing human girl.

Character: Shimogamo Yasaburou 下鴨矢三郎
Anime: Uchouten Kazoku 有頂天家族 (Episode 1)

Context: in spite of looking like a girl in this scene, Yasaburou is actually male, as you can guess from the fact his name ends in ~saburou ～三郎, and from the fact he sits in agura position despite wearing a skirt.

Someone sitting on a chair with their legs crossed is also called agura, so it isn't necessarily about the floor.

Shinjou Akane 新条アカネ, sitting cross-legged, example of agura 胡座.

Character: Shinjou Akane 新条アカネ
Anime: SSSS.GRIDMAN (Episode 2)

In rope bondage (shibari 縛り), agura is the name of a tie in which a person's legs are bound crossed, called agura shibari あぐら縛り.

【リク消化】戦国無双2石田三成緊縛※腐

Despite the above, the word agura doesn't apply to all situations in which someone sits with their legs crossed.

"Legs Crossed" in Japanese

The term agura only refers to a specific sitting position on the floor. It doesn't refer to sitting with your legs crossed on a chair in the usual way, for example.

Nishikino Maki 西木野真姫, example sitting "crossing legs," ashikumi 足組み.

Character: Nishikino Maki 西木野真姫
Anime: Love Live! School Idol Project (Episode 2, Stitch)

isu ni suwatte ashi wo kumu
椅子に座って足を組む
To sit on a chair and cross [one's] legs.

See "legs crossed" in Japanese for examples of this.

Another position that's not called agura is that meditation pose, which is related to Buddhism, and in yoga is called "lotus position." One difference is that besides crossing ones legs, the feet soles face up.

Senjougahara Hitagi 戦場ヶ原ひたぎ, example of character sitting in the lotus position of yoga, used for meditation, also called kekkafuza 結跏趺坐.

Character: Senjougahara Hitagi 戦場ヶ原ひたぎ
Anime: Koyomimonogatari 暦物語 (Episode 4, Stitch)

kekkafuza
結跏趺坐, or 結加趺坐
Lotus position. (in yoga)
Sitting with legs crosses, both soles facing up.
hankafuza
半跏趺坐
A variant of the lotus position in which one doesn't cross their legs, just places one leg over the other.

Kanji

The word agura あぐら is normally spelled with hiragana. It can be written with kanji, as agura 胡座. The meanings of the kanji are:

ko
胡
Foreigners. Specifically barbarians around China.
za
座
Seat.

Note that the readings of the kanji don't match the word agura, because it's an ateji 当て字, due to its origins.

Origin

The word agura originates in a certain type of folding chair originating from China^{(kanjibunka.com)}, which wasn't actually invented in China, but originates further west, in Mesopotamia around 2000–1800 BCE.^{(中央大学公式YouTube:starting from 19m43s)}

The folding chair makes a cross shape, or rather, an X shape when it's unfolded, just like the shape your legs make when crossed, so that's the connection between the two things.

Anime: Girls und Panzer, ガールズ＆パンツァー (OVA, Episode 2, サバイバル・ウォー！)

Context: the correct orientation of this chair is, ironically, with the X facing sideways.^{(wakabyashi-jiin.com)}

Work: a psykter featuring Dionysos and his thiasus by the Antimenes Painter
Source: Wikimedia, Louvre Museum (in public domain, photographer: Jastrow)

Context: Dionysos sitting on an agura, painted in Greece, circa 525–500 BCE.

The name of such chair in Chinese would be 胡床 (húchuáng?). In Japanese it was called agura 胡床, so from the Japanese name of this Chinese chair came the term for sitting with one's legs crossed in Japanese.

Note the difference between 胡床 and 胡座: the chair is spelled with the kanji for "floor," yuka 床, while the sitting pose is spelled with the kanji for "to sit," suwaru 座る.

Examples

For reference, some other examples:

Excel エクセル, example of pouting, 3-shaped mouth, "anger mark," ikari maaku 怒りマーク.

Character: Excel エクセル
Anime: Excel♥Saga, エクセル♥サーガ (Episode 4)

Context: Excel pouting with 3 mouth an anger mark on her forehead in agura position.

Himura Kenshin 緋村剣心, example of tate-hiza 立て膝, sitting with one knee up.

Anime: Samurai X, Rurouni Kenshin: Meiji Kenkaku Romantan るろうに剣心 -明治剣客浪漫譚- (Episode 6)

Context: various characters sitting on the floor, most in seiza position, except for the character in tate-hiza 立膝 in the front, and the one wearing a sarashi さらし in agura position.