Several parts combine into one character.

回 is a picture of water swirling in a whirlpool — the inner 口 and outer 囗 are two nested coils. From spinning round and returning to the start grew the senses "to turn, to return, a time (occurrence)."

Mandarin: huí, 2nd tone. 回家 (huí jiā, to go home), 回来 (huílái, to come back), 回答 (huídá, to answer), 一回 (yī huí, once). China's Muslim minority is called 回族 (Huízú, the Hui people). A common character, ranked 172nd.

Japanese: on-readings カイ (kai) and エ (e), kun まわ.る (mawaru) and まわ.す (mawasu). 回る (mawaru, to turn), 一回 (ikkai, once), 回転 (kaiten, rotation), 回答 (kaitō, a reply). Conveyor-belt sushi is 回転寿司 (kaitenzushi, "rotating sushi").

Korean hanja-sound "hoe": 回轉 (hoejeon, rotation), 回復 (hoebok, recovery), 回答 (hoedap, a reply), 一回 (ilhoe, once), 撤回 (cheolhoe, withdrawal). Counting occurrences uses 一回 (ilhoe), 二回 (ihoe).

Memory aid: a whirlpool coiling round in two nested rings — turning back to where it began.