Several parts combine into one character.

A character with split etymology. Originally 冬 pictured a thread tied at both ends — the same "end of thread" image as 終 (end, from earlier batch). Both 冬 and 終 share a common ancestor — the knot that closes off a series. As the meanings diverged, 冬 absorbed 冫 (ice — the two-dot ice radical) at the bottom, encoding "the end of the year + frost" = winter. Identical across 繁體 / 新字体 / 简体.

Four-season set complete with this entry: 春夏秋冬 (spring-summer-autumn-winter), the foundational temporal sequence in CJK culture. The phrase 春夏秋冬 reads in order as shun-ka-shū-tō in Japanese — the entire calendar in four syllables.

Mandarin: dōng, level 1st tone. 冬天 (dōngtiān, winter), 冬季 (dōngjì, winter season), 冬至 (Dōngzhì, winter solstice — December 21–22, traditionally celebrated with dumplings in northern China and tangyuan glutinous rice balls in the south), 冬眠 (dōngmián, hibernation), 冬奥会 (Dōng'àohuì, Winter Olympics).

Japanese: on-reading トウ (tō) for compounds — 冬季 (tōki, winter season), 冬至 (tōji, winter solstice), 冬眠 (tōmin, hibernation), 立冬 (rittō, start of winter — November 7). Kun-reading ふゆ (fuyu) is the everyday word — 冬 (fuyu, winter), 冬休み (fuyuyasumi, winter vacation), 真冬 (mafuyu, midwinter), 冬服 (fuyufuku, winter clothes / winter uniform).

With 冬 we complete the four-season vocabulary that English-speaking learners can immediately use: spring 春 (haru/chūn), summer 夏 (natsu/xià), autumn 秋 (aki/qiū), winter 冬 (fuyu/dōng).

Memory aid: a knot at the year's end, with ice crystals at the bottom — winter as the close of the cycle.