Several parts combine into one character.

美 is a compound ideograph: 羊 (sheep) sitting atop 大 (big). The composite meaning is breathtaking in its bluntness — "a big sheep." To ancient nomadic and pastoral peoples, a fat, healthy sheep was the most immediate sign of prosperity, abundance, and good fortune. From this concrete agricultural ideal grew the abstract concepts of beauty, deliciousness, and virtue all clustered in one character. To this day, 美 is filed under the 羊 (sheep) radical in Chinese dictionaries — a small lexicographical reminder of the character's pastoral origin.

The semantic doubling of "beautiful" + "delicious" runs through the entire CJK family. The character carries equal authority in art criticism (美術 fine art), human appearance (美人 beautiful person), and food praise (美味 delicious flavor).

Korean reading "mi." 美術 (misul, fine art), 美人 (miin, beautiful person — typically a woman), 優美 (umi, graceful), 甘美 (gammi, sweet — often used for music or taste), 美學 (mihak, aesthetics — the philosophy branch). In Korea, the "beautiful" sense dominates; the "delicious" sense survives mainly in 美味 (mimi).

Mandarin měi, 3rd tone. 美丽 (měilì, beautiful), 美食 (měishí, gourmet food / fine cuisine), 美女 (měinǚ, beautiful woman / pretty girl — used as a casual address in mainland China), 完美 (wánměi, perfect). Most consequentially: 美国 (Měiguó, "Beautiful Country" = United States of America). It is a common misconception that this is a flattering name; in fact, the "Měi" in 美国 is purely a phonetic borrowing from the "me-" sound in "America" — Chinese chose 美 (a high-status character) over alternatives like 米 (rice) for the transliteration. This contrasts with how Mandarin renders other countries (Japan = 日本 "sun-origin"; Korea = 韩国 "Han nation").

Japanese on-reading ビ (bi) — 美術 (bijutsu, fine art), 美人 (bijin, beautiful person), 美容 (biyō, beauty / cosmetology), 美徳 (bitoku, virtue), 美学 (bigaku, aesthetics). Kun-reading うつくしい (utsukushii, "beautiful") — a high-register adjective; in everyday Japanese, きれい (kirei) is more common for casual beauty, while 美しい carries gravity and is reserved for striking, elevated beauty (a sunset, a temple, a perfect kanji stroke). And the most famous lexical curiosity: 美味しい reads as おいしい (oishii, "delicious") — a 熟字訓 (jukujikun) reading where the kanji compound is given a native Japanese reading rather than its Chinese phonetic. 美 + 味 = "beautiful flavor" → oishii is the sound of every Japanese person's reaction to a good meal.

Memory aid: a big (大) sheep (羊) — agricultural prosperity → beauty in every dimension.