noun
great favor; deep obligation
Formal noun expressing profound gratitude for a significant kindness or favor received. Often used in letters, speeches, or formal acknowledgments.
ご厚恩に深く感謝いたします。
I am deeply grateful for your great kindness.
彼の厚恩は一生忘れません。
I will never forget his great favor for the rest of my life.
Compound of 厚 (thick, deep, profound) and 恩 (favor, kindness). The exact historical derivation is uncertain, but the combination naturally conveys a deep sense of gratitude.