秘密 is a curious word because both characters are pronounced mì yet they are different from each other. Given that there are so many homophonous characters in Chinese, I'm curious if there's any other combinations of them into words, and if not why did 秘密 become the exception?
Alliteration (双声) seems to be quite common in Putonghua, and this is an extreme form of alliteration.
It's interesting how all these examples use the fourth tone.
There are more words like this but they tend to be less commonly used or literary words (书面语). Eg: 幽忧* yōuyōu /distressed/laden with grief/
In this answer I've added a (*) to such words.
Edit: Mou某 gave two other good examples:
And these aren't fourth tone, which is nice.
Edit 2: 全权 quánquán /full powers/total authority/plenipotentiary powers/
(from Becky 李蓓 's comment)
- 意义 yìyì /sense/meaning/significance/importance/;
- 意译 yìyì /meaning (of foreign expression)/translation of the meaning (as opposed to literal translation 直譯|直译)/paraphrase/free translation/;
- 异议 yìyì /objection/dissent/
(from Olle Linge's comment)
Edit 4: Not a two-character word, but a chengyu that starts with two homonyms: 屋乌推爱* wūwūtuīài - it's a variant of the much more well-known chengyu 爱屋及乌 àiwūjíwū /lit. love the house and its crow (idiom); involvement with sb and everyone connected/Love me, love my dog./
Both versions feature the homonyms 屋 / 乌. It would be interesting to focus on other similar chengyu - perhaps this a topic for a separate question here later on. (2022-06-15)