一切經音義 9.248

9.248

豪氂（又作毫同胡高反下古文氂䋘二形今作𣮉同力之反漢書不失毫氂孟康注毫兔毫也十毫曰氂今皆作氂亦由古字通用也然非通用也然非字體也）。

豪氂 [hairbreadth / minute amount]: 豪 is also written 毫; [both are pronounced with the] fanqie 胡高 (háo). As for the second character, ancient texts have two forms: 氂 and䋘; it is now written 𣮉, with the fanqie 力之 (lí). The Book of Han says: "Without losing a hairbreadth (毫氂)." Meng Kang's commentary says: "毫 is the fine hair of a hare. Ten 毫 make one 氂." Nowadays, it is universally written 氂; this also stems from the interchange of ancient characters, yet this is not an interchange, but rather not the proper character form.