一切經音義 6.256

6.256

唐捐（上徒即反字書云唐虛玉篇云唐徒也考聲云言而不當也說文云唐大言也從口庚古行反聲也下悅淵反）。

唐捐 ("to be in vain"): The first character has the fanqie reading [d- + -ɑŋ = táng] (徒即反 [read 徒郎反]). The Zishu says: "唐 means empty." The Yupian says: "唐 means vain." The Kaosheng says: "To speak inappropriately." The Shuowen says: "唐 means boasting words. It is formed with the radical 口 ('mouth') and 庚 (fanqie 古行反) as phonetic." The second character has the fanqie reading [j- + -iuɛn = juān] (悅淵反).