also: ようたい
noun
key point; essence; crucial point
Refers to the most important or central point of a matter, often used in formal or explanatory contexts.
この問題の要諦は、資金不足にある。
The key point of this problem lies in the lack of funds.
彼の話の要諦をまとめると
To summarize the essence of his talk, reform is necessary.
要 (essential) + 諦 (truth, essence). The exact historical derivation is uncertain, but the compound conveys the idea of the ultimate or most important truth.