妹

妹 (Kangxi radical 38, 女+5, 8 strokes, cangjie input 女十木 (VJD), four-corner 4549₀, composition ⿰女未)

Stroke order

• Kangxi Dictionary: page 257, character 28
• Dai Kanwa Jiten: character 6138
• Dae Jaweon: page 522, character 23
• Hanyu Da Zidian (first edition): volume 2, page 1034, character 6
• Unihan data for U+59B9

Historical forms of the character 妹
Shang	Western Zhou	Shuowen Jiezi (compiled in Han)
Oracle bone script	Bronze inscriptions	Small seal script

Phono-semantic compound (形聲／形声, OC *mɯːds) : semantic 女 (“female, woman”) + phonetic 未 (OC *mɯds).

Probably Sino-Tibetan. Proposed etymologies:

• STEDT relates it to Proto-Sino-Tibetan *mi (“girl; female; feminine suffix”), whence Apatani nyimii (“girl; woman; female”), Proto-Loloish *C-mi² (“woman”), Proto-Karen *hmɨᴮ (“female; woman”).
• Schuessler (2007) compares it to Burmese မ (ma., “sister”) (whence အစ်မ (acma., “elder sister”), ညီမ (nyima., “younger sister”)), Miju ku-mai- (“woman”), Tibetan བུད་མེད (bud med, “woman”), and also Mizo hmei (“concubine”) (> Mizo hmei-chhia (“woman; wife”)), which STEDT relates to Proto-Sino-Tibetan *s-maj (“widow, widower”) instead.

妹

1. younger sister
2. girl; young female
3. (Hakka) daughter
4. a surname

• → Thai: หมวย (mǔai, “younger sister”) (said by Chinese ethnicity)

• “妹”, in 漢語多功能字庫 (Multi-function Chinese Character Database)‎, 香港中文大學 (the Chinese University of Hong Kong), 2014–

(grade 2 “Kyōiku” kanji)

• Go-on: まい (mai, Jōyō); め (me)
• Kan-on: ばい (bai)
• Kun: いもうと (imōto, 妹, Jōyō)^{←いも𛄟と (imowuto, 妹, historical)←いもひと (imofito, 妹, ancient)}; いも (imo, 妹)
• Nanori: せ (se)

⟨imo₁⟩ → */imʷo/ → /imo/

From Old Japanese 妹 (imo₁). First cited in the Kojiki of 712.[1]

Speculatively, may be related to terms such as 女 (me₁, womi₁na, “woman”), 嫗 (omi₁na, “elderly woman”), and 母 (omo, “mother”), wherein the medial /-m-/ appears to signify woman, female.[1] However, the difference in vowel values presents a difficulty.

• (Tokyo) い​も [íꜜmò] (Atamadaka – [1])[2]
• IPA^(key): [imo̞]

妹(いも) • (imo) 

1. (archaic, said from a male speaker) a close female companion
   1. one's sister regardless of age difference
   2. one's lover or sweetheart who is the subject of marriage or is already married
      • 905–914, Kokin Wakashū (book 11, poem 485)

        かりごもの思(おも)ひ乱(みだ)れて我(われ)恋(こ)ふといも知(し)るらめや人(ひと)し告(つ)げずは

        karigomo no omoimidarete ware kou to imo shirurame ya hito shi tsugezu wa

        (please add an English translation of this example)

2. (archaic, said from a female speaker) a close female companion

• 兄(せ) (se, “close male companion, man”)

/imo ɸito/ → /imowito/ → */imowuto/ → /imoːto/

Originally a compound of 妹 (imo, “sister, close female companion”) +‎ 人 (hito, “person”).[1][2][3][4] First cited in The Tales of Ise of the early 900s.[1]

This is an instance of ウ音便 (u onbin, “u sound shift”), found in terms with bilabial consonants (/m/, /b/, /w/) followed by i; commonly seen in terms such as 玄人 (kurōto, “professional”), 素人 (shirōto, “amateur”), or possibly, 相撲 (sumō, “sumo”).

• (Tokyo) いもーと​ [ìmóótóꜜ] (Odaka – [4])[2][3][5]
• IPA^(key): [imo̞ːto̞]

妹(いもうと) • (imōto) 

1. one's own younger sister

   Antonym: 姉 (ane, “older sister”)

   • 2005 January 10, Izawa, Hiroshi with Yamada, Kotaro, “第(だい)34話(わ)　復(ふく)讐(しゅう)の槍(やり) [Chapter 34: The Lance of Vengeance]”, in ファイアーエムブレム 覇者の剣 [Fire Emblem: Sword of Champions], volume 9 (fiction), Tokyo: Shueisha, →ISBN, page 60:

     妹(いもうと)の仇(かたき)だ！何(なん)万(まん)人(にん)だろうが地(じ)獄(ごく)へ送(おく)ってやる‼

     Imōto no kataki da! Nanmannin darō ga jigoku e okutte yaru‼

     This is for my sister! Keep coming, all of you! I’ll send you all straight to hell‼

   • 2014 January 17, Ōima Yoshitoki, “第(だい)14話(わ)　西(にし)宮(みや)結(ゆ)絃(づる) [Chapter 14: Nishimiya Yuzuru]”, in 聲(こえ)の形(かたち) (聲(こえ)の形(かたち)) [A Silent Voice], volume 2 (fiction), Tokyo: Kodansha, →ISBN, page 60:

     永(なが)束(つか)君(くん)　「少(しょう)年(ねん)」じゃない…西(にし)宮(みや)の妹(いもうと)だってよ

     Nagatsuka-kun “Shōnen” ja nai… Nishimiya no imōto da tte yo

     Nagatsuka-kun. That's not a "boy"… Nishimiya said that's her sister.

2. the wife of one's younger brother; one's sister-in-law

   Synonym: 義妹 (gimai)

3. a younger female
4. (archaic, said from a male speaker) one's sister regardless of age difference

   Antonym: 兄人 (shōto)

(alternative reading hiragana いもっ, rōmaji imo')

1. (Kagoshima) younger sister

Analyzed as a shortening of imōto, itself a compound 妹 (imo, “sister, close female companion”) +‎ 人 (hito, “person”).[1][3][4][6]

Appears in The Tale of Heiji, written around the mid-12th century.[3] May be much older, as this reading is also included in kun'yomi glosses for the Nihon Shoki of 720 (although the manuscripts with the glosses themselves are not as old).[1]

妹(いもと) • (imoto)