Eel

It means eel, read うなぎ (unagi) in Japanese. The character is built from 魚, the fish marker, and 曼, which supplies its sound. The Japanese word appears as 武奈伎/牟奈伎 in the 8th-century Man’yōshū, an early poetry anthology; that dates the word, not necessarily the first appearance of this exact written form.

In Japanese food writing, 鰻 names both the fish and dishes made from it, such as eel served over rice or grilled eel.

why do Japanese eat 鰻 on 土用の丑の日?

It is a seasonal custom, not 鰻’s basic meaning. On 土用の丑の日—the summer Day of the Ox—people eat eel as a nourishing seasonal food. The Edo period established the custom. A popular origin story credits Hiraga Gennai with suggesting an eel shop’s sign; treat that as an attribution, not settled authorship.

The surrounding cue changes the reading: 鰻 on a menu names eel or an eel dish, while beside 土用の丑の日 it points to the seasonal custom and a wish for summer health.

what does 鰻 mean in a message?

Read it as eel first; surrounding words identify the language and dish. In Japanese, 鰻 is read うなぎ (unagi). Traditional Chinese uses 鰻, read mán in Mandarin pinyin; simplified Chinese writes 鳗. The forms mark writing conventions, not different animals.

鱔 and 鱓 are separate Chinese fish terms that reference works sometimes mix with 鰻; they are not automatic spelling variants. If a message names a particular species, keep the sender’s character.