理由的理: specify a character by context
I would call it 釐清 (to clarify)

釐清 這個 'li' 是 理由的理, 不是 里程的里
to clarify this 'li'  is 理 for 理由, not 里 for 里程

or
闡明 (to clarify )

闡明 這個 'li' 是理由的理, 不是 里程的里
to clarify this 'li' is 理 for 理由, not 里 for 里程

神秘德里克 wrote:

提问人问专门的词，这两个词也不是说专门表示这件事情。应该是没有什么专门的词专门表达这件事情。

I agree there is no specific term for 'specify a character by context' .
'specify a character by context' is an act of '釐清' or '闡明' a character

&quot;你叫 Huáng Yuán? 請問是那一個 Yuán?&quot; (Your name is Huáng Yuán? May I ask which yuán is that?)

&quot;To clarify (釐清/闡明) which 'Yuán' is in his name, 黃源 said: 'it is the 源 in 水源&quot;