同訓異字 (Đunh·Hùn·Ỳ·Đừ)- Doukuniji
This term refers to characters which are pronounced the same and have the same etymology, but are written with two different hanzi. There are a variety of reasons why this may occur. Some of the more common ones being that Vietnamese made a distinction between the words, the words were perceived as having different etymologies, or that one character was chosen for aesthetic reasons. Below are all of the ones (aside from those for Bõ discussed earlier) that I’ve been able to find so far of this occurrence. I know for a fact there are more and hopefully I’ll be able to update this post with more of them as I find them.
Ả: 𨕭 vs 𨑗
The spelling 𨕭 is used as a preposition and means roughly “on/above” whereas the spelling 𨑗 occurs as a noun/adjective/adverb and means “up/upper/above/etc”. The reason for this word’s having 2 hanzi is due to the preposition for “under/below”, 𤲂 (ã), being different from the word for “down/lower/below/etc” which is 𨑜 (gũ). Additionally, by spelling the non-prepositions for these words as 𨑗 & 𨑜, an easy dichotomy between the terms can be observed just from looking at them.
Cá: 果 vs. 棵
果 is the most common spelling of this word and has the general meaning of “fruit”. 棵 is only used as a counter for plants. Its hanzi was chosen as both Mandarin and Vietnamese (only in Chữ Nôm) make the same distinction between these two characters.
Cà: 丐 vs. 个 vs. 個
丐 is the most common spelling of this word and is used as a counter alongside native numerals. By contrast, 个 is used as a counter alongside Sinic numerals and 個 is used practically only in word for "individual", 個人 (cà·nin) and its derivatives. The reason for this distinction is due to Vietnamese having a distinction between 丐 and 個. The simplified 个 became used in counters due to its simplicity while 個 remain used in 個人 due to it not taking too long to write in the compound, 个人 looking a bit odd in context, and later on due to a perceived difference in etymology.
Cã: 𩷛 vs. 犀
𩷛 is the usual spelling for this term and is the Ởnh·Vú word for “scale”. The hanzi 犀 (which is also the hanzi for rhinoceros) is only used with this pronunciation in the word for “pangolin”, 犀獸 (cã·đrí) due to the fact that the Vietnamese term for pangolin is written with this hanzi.
Chãy: 𦵙 vs. 𥑂
When written 𦵙, this word means either “sap/resin” or “plastic”. When written 𥑂, it instead has the meaning of “pitch/tar”. The reason for the split in hanzi is due to Vietnamese making a distinction between them.
Cuich: 𤿦 vs. 𦡮
𤿦 is the most commonly used hanzi for this term. It means “skin/hide/leather” and is used in the vast majority of compounds. The hanzi 𦡮 only occurs in the term for “lung”: 𦡮𥐈 (cuich·só). This hanzi was chosen as it was presumed to have a different etymology than the word for skin.
Dõc: 𣗓 vs. 𤴓
𣗓 is the word for “still/yet” whereas 𤴓 is the topic marker. These two terms were perceived as having a different etymology and so were written with two different characters.
Gữ: 𤎜 vs. 畑
𤎜 is the word for “morning” and is the most common spelling of the term in compounds. 畑 occurs in the Ởnh·Vú word for “light”: 畑光 (gữ·canh). Originally the word for light was simply gữ and was written with 畑 to distinguish it from 𤎜. 光 was added later on in the language’s development to further distinguish the two in speaking.
Hãnh: 炭 vs. 碳
炭 is the spelling of the word for “charcoal”, whereas 碳 is the spelling of the word for “carbon”. This difference in hanzi is due to Mandarin having the same distinction.
Hãnh: 邊 vs. 坡
邊 is by far the most common spelling of this term and means “riverbank”. 坡 only occurs in the expressions 𨕭坡 (ả hãnh), meaning “ashore”, and 𨖲坡 (đì hãnh), meaning “stranded/beached”. Originally hãnh, when written as 邊, had the meaning of edge whereas 坡 was used for the meaning of shore. Over time the spelling 邊 became more and more common. Eventually the Sinic pronunciation of 邊, pen, became used for the meaning of edge, while the pronunciation hãnh became used to mean almost exclusively riverbank. 坡 became used for the two terms it is, as both of these terms can refer to other shores/banks aside from those of rivers.
Pun: 丿vs. 分
The hanzi 丿 is used exclusively for the word for “minute” and its derivatives, while 分 occurs in all other words. Minute came to be written as 丿due to the term being written with the character in Chữ Nôm, in addition to the character being extremely easy to write.
Sả: 𠅎 vs.除
When spelled as 𠅎 this term means “to lose”, whereas the spelling 除 is used for the term “except”. The use of two different hanzi is due to Vietnamese having 2 different words for these terms.
Sữm: 摀 vs. 𠑋
摀 is the word for “umbrella” and is overwhelmingly the most common spelling of this term. The hanzi 𠑋 only occurs in the term 神𠑋 (yảnh·sữm) which is the Ởnh·Vú word for “lọng dù”, which is a kind of Vietnamese umbrella with a long stem used in certain royal/religious ceremonies
. The difference in hanzi is due to Vietnamese maintaining a difference between these two terms.
Tã: 𠓨 vs. 𨤔
As discussed in the posts above, 𠓨 is a verbal complement meaning “enter”. 𨤔 on the other hand means “to look like”. The use of different hanzi is due to the terms being perceived as having different etymologies.
Tãc: 招 vs. 尞
招 is the generic Ởnh·Vú word for "to hang/hoist/raise/put up/fly" but also means to hang a criminal. 尞 has the same meaning of "to hang/hoist/raise/put up/fly" but only refers to flags. The reason for this distinction is due to Vietnamese having this distinction in Chữ Nôm, despite not having this distinction in pronunciation.