1. Meaning:

circle, yen, round

2. Readings:

• Kunyomi (訓読み): まど、 まど-か、 まる、 まる-い、 まろ-やか
• Onyomi (音読み): エン
• Japanese names: つぶら、 のぶ、 まどか、 みつ
• Chinese reading: yuán

3. Etymology

形声文字 (けいせいもじ, keisei moji, i.e. characters combining semantic and phonetic elements). The traditional form of 円 is 圓, whose most ancient form is 員. The other form of 員 was surrounded by the 囗 (い, i, enclosure radical). Both 員 and 圓 appear in the book entitled 說文解字 (shūo wén jiè zì, i.e. “Explaining Simple (Characters) and Analyzing Compound Characters”) from the 2nd century C.E., compiled by a philologist of the Han dynasty (漢朝, 206 BCE – 220 CE), 許慎 (Xǔ Shèn, ca. 58 C.E. – ca. 147 C.E.). 說文解字 contains over 9000 character forms, including the most ancient ones, (Figure 1 and 2).

員, whose original sound was えん (or more precisely ゑん, i.e. “(w)en)”), often appears as a rhyme in Chinese classical poetry, usually as two identical kanji that bear the sound “(w)en”. They were repeated through verses, hence the later reference to a circle or a round object. In Japanese, such a repetitive rhyme is called 畳韻 (じょういん, jōin, i.e. “stacking rhyme”). Note that the construction of the second kanji in the phrase 畳韻 is 音 (おん, on, sound) + 員 (えん, en, in here: “en” sound). Consequently, 畳韻 is a “stacking (repeatedly used) “en” sound”.

The bottom part of the kanji 員 was derived from the shape of a bronze tripod (鼎, てい, tei), (Figure 1). However, since the tripods may have different non-round shapes, the ○ compound was added to emphasize that 員 represents a round tripod (円鼎, えんてい, entei). The 囗 (い) radical further emphasizes the roundness.

It is also important to point out that the hand written form of the 圓 differs from the 活字 (かつじ, katsuji, i.e. printed font). The top part (originally: ○, i.e. a circle) imitates the modern 厶部（しぶ、shibu）kanji radical (Figure 3, 4, 5 and 6). It further proves that the rectangle shape on the top of the character 員 is not 口 (くち, kuchi, “mouth”), but in fact a remnant of the ○. One may wonder why its round shape was replaced with a triangle. Simply, the Clerical script (隷書, れいしょ, reisho) was much more squat and square than the great Seal script (篆書, てんしょ, tensho), and many supple curves were replaced with strokes written at steep angles with abrupt turns (Figure 3).

Lastly, please note, that the character 圓 is not related etymologically to 圜 (えん, en, i.e. “round”), even though both of them have similar meanings and sounds.

4. Selected historical forms of 円

Figure 1. 金文 (きんぶん, kinbun, i.e. “text on metal”) form of the character 員. It is a pictograph of a bronze tripod with a 〇 at the top, indicating its “roundness” Found in the 說文解字 (shūo wén jiě zì, i.e. “Explaining Simple (Characters) and Analyzing Compound Characters”), by a philologist 許慎 (Xǔ Shèn, ca. 58 C.E. – ca. 147 C.E.).

Figure 2. Great seal script (大篆, だいてん, daiten) form of the character 圓 Found in the 說文解字 (shuō wén jiě zì, i.e. “Explaining Simple (Characters) and Analyzing Compound Characters”), by a philologist 許慎 (Xǔ Shèn, ca. 58 C.E. – ca. 147 C.E.).

Figure 3. Clerical script from the Song of the Southern Dynasties (劉宋, 420 – 479 C.E.). Ink rubbing of the character 圓 from the stele 劉懷民墓誌 (liú huái mín mù zhì), 464 C.E. Note the triangle shape above the 貝 (かい, kai, i.e. “shell”, “shellfish”) radical.

Figure 4. Cursive script (草書, そうしょ, sōsho) of the character 圓. Ink rubbing of the calligraphy by 康里巙巙 (Kāng Lǐ Náonáo), Yuan dynasty period (元朝, 1271 – 1368)

Figure 5. Ink rubbing of the character 圓 in standard script (楷書, かいしょ, kaisho) taken from the stele in the Mausoleum of Confucius (孔子廟堂碑, Chinese: Kǒng Zǐ miào táng bēi), early 7th century C.E.

Figure 6. Semi-cursive script (行書, ぎょうしょ, gyōsho) of the character 圓. An ink rubbing from the calligraphy entitled 文皇哀冊 (wén huáng āi cè), which was a lament over the death of the Emperor Taizong (太宗, 626 – 649), written by 褚遂良 (Chǔ Suìliáng, 596 – 658), in the early Tang Dynasty (唐朝, 618 – 907).

5. Useful phrases

• 円周 (えんしゅう, enshū) – circumference
• 円相場 (えんそうば, ensōba) – yen exchange rate
• 円さ (まるさ, marusa) – roundess
• 円満な (えんまんな, enman na) – perfect, harmonious, well-rounded