also: じんこう
na-adjective, noun
deeply sincere; profound; heartfelt
Formal or literary term describing deep sincerity, profound feeling, or heartfelt emotion. Often used in written language or formal speech.
彼の深厚な友情に感謝している。
I am grateful for his profound friendship.
深厚なるご支援を賜り、誠にありがとうございます
We are truly grateful for your deeply sincere support.
Compound of 深 (deep) and 厚 (thick, generous), suggesting a deep and generous sincerity. The reading しんこう is the standard on'yomi; じんこう is a less common variant.