1A maple tree (Acer), especially one with deeply lobed, hand-shaped leaves that turn red in autumn. Often written in kana as もみじ.
庭に大きな紅葉の木が一本ある。
There is one big maple tree in the garden.
もみじの葉は手のひらのような形をしている。
A maple leaf is shaped like the palm of a hand.
公園の紅葉がすっかり赤くなった。
The maples in the park have turned completely red.
2The autumn turning of leaves to red or yellow, or the colored leaves themselves; enjoyed as an outing in activities like momijigari (leaf viewing).
週末はもみじを見に山へ行こう。
Let's go to the mountains this weekend to see the autumn leaves.
川沿いの紅葉がとてもきれいだ。
The autumn leaves along the river are really beautiful.
台風でせっかくの紅葉が散ってしまった。
The typhoon scattered the lovely autumn leaves.
3A traditional layered-color scheme (kasane) for garments such as kimono, evoking autumn foliage; a classical and somewhat specialized color term.
平安時代の女房装束には紅葉の襲がよく用いられた。
The momiji color layering was often used in the court ladies' costumes of the Heian period.
4A slang word for venison (deer meat), derived from the hanafuda pairing of deer and maple; still used in expressions like momiji-nabe (venison hot pot).
冬はもみじ鍋で鹿肉を味わうのが楽しみだ。
In winter I look forward to enjoying venison in a momiji hot pot.
この店ではもみじ、つまり鹿肉の料理を出している。
This restaurant serves momiji — that is, venison dishes.