The ultimate derivation remains unclear. The term occasionally appears in texts from the Heian period (794–1185 CE) with the phonetic spelling mumashi (in the classical terminal form), suggesting a possible pronunciation of */mmasi/ with an emphasized initial /mm/ sound, similar to the reconstructed readings for 馬 (*mma, “horse”) and 梅 (*mme, “plum”). The resulting reconstructed adjective stem of *mma- could indicate a derivation from onomatopoeia; compare English mmm as an expression of approval for something tasty.
Alternatively, umai is listed in some sources as perhaps deriving from verb 熟む (umu, “to ripen, to become ripe”). There is a derived compound term where the meaning is clearly from the adjective, and the spelling uses the 熟 kanji from the verb. However, the verb does not appear in historical sources with an emphatic initial /mm/, and it seems to be cognate with 膿む (umu, “to fester, to become pussy, to produce pus”, intransitive), possibly also with 生む, 産む (umu, “to bear, to give birth to; to produce”, transitive).
うまい (-i inflection, rōmaji umai)
- 上手い, 巧い: good at something, skillful
- 美味い, 旨い, 甘い: delicious, tasty
- 旨い: favorable, preferable, good
- 旨い: profitable
- Kabushikinakagainin to wa umai shigoto desu yo.
- Being a stockbroker is profitable work.
- (uncommon) 旨い: thoughtless, foolish, lackadaisical, slipshod, short-sighted
This term is more common in masculine speech, and may have more casual connotations. The common gender-neutral and polite term for the skillful sense is 上手 (jōzu), and for the delicious sense, 美味しい (oishii).
- うまい (umai) (熟寝, 熟睡, 味寝): a deep sleep, a refreshing sleep
- うまいい (umaī) (味飯): tasty rice
- うまうま (umauma) (旨旨): (baby talk) tasty, delicious; milk; the mother's breast
- うまき (umaki) (味酒): delicious saké
- うまくさい (umakusai) (旨臭い): smelling delicious; seeming favorable
- うまくち (umakuchi) (甘口): sweet flavor (as of a wine or sauce, in contrast to dry or sour); convincing words, flattery
- うまさ (umasa) (旨さ): deliciousness, tastiness
- うまさけ (umasake), うまざけ (umazake) (旨酒, 味酒, 美酒): delicious saké
- うまに (umani) (甘煮, 旨煮): sweet nimono (a kind of traditional Japanese simmered dish)
- うまひと (umahito) (味人, 貴人): someone from a good family; a noble, an aristocrat
- うまみ (umami) (旨味): taste, flavor; savor, savoriness; attractiveness, charm; profit
- うまら (umara) (旨ら, 甘ら, 美ら): (archaic) delicious, tasty; pleasant, comfortable
- ^ c. 759, Man'yōshū (book 16, poem 3857), text here
- 1988, 国語大辞典（新装版） (Kokugo Dai Jiten, Revised Edition) (in Japanese), Tōkyō: Shogakukan
- ^ Gogen Allguide, entry here (in Japanese)
- 2006, 大辞林 (Daijirin), Third Edition (in Japanese), Tōkyō: Sanseidō, →ISBN
- ^ 1998, NHK日本語発音アクセント辞典 (NHK Japanese Pronunciation Accent Dictionary) (in Japanese), Tōkyō: NHK, →ISBN
- ^ 1997, 新明解国語辞典 (Shin Meikai Kokugo Jiten), Fifth Edition (in Japanese), Tōkyō: Sanseidō, →ISBN
- ^ 1995, 大辞泉 (Daijisen) (in Japanese), Tōkyō: Shogakukan, →ISBN