栃
とち
horse chestnut, (kokuji)
JLPT0 G7 S9 F1427
栃 is a character with a particularly convoluted etymology. The variant form 杤 combines 木 tree/wood + 万 ten thousand. One element of traditional shrine and farmhouse architecture in Japan is a pair of crossing pieces of timber on the roof atop the respective ends of the ridgepole. This feature is designated ちぎ (千木), 千 and 木 being pronounced with their KUN readings ち and き (here in the voiced consonant form ぎ). As it happened, a shrine now located within the Tochigi castle precincts had such pairs of ちぎ. Appending the native Japanese term for (と) yields とちぎ, while prefixing the character for (十) to 千木 yields 十千木. Read literally, the combination 十千 means "ten thousand," but in Han/Chinese characters ten thousand is written with the single character 万. Thus was devised the Made-in-Japan character 杤, retaining the 木 portion of 十千木 while replacing 十千 with 万. During the Meiji Era, however, 万 was superseded by the element seen in the left-hand side of 励, 栃 becoming the standard form of the character. As for the tree known as とち (short for とちのき), this is the (Japanese) *horse chestnut* (Aesculus turbinata). For horse chestnut, compare 橡, which also has the KUN reading とち.
[Full Kanji Etymology List]