Is び the reading for a productive suffix 〜日?

Question

In cases where 日 is productively attached as a suffix to an already complete word, what is the canonical reading of this character? I mean cases, when a connecting article の is dropped and 日 becomes a suffix, but does not form an entirely new word with its own meaning and reading.

• 指定日 していび 読み方は
• 予定日 よていび 読み方は
• 出発日 しゅっぱつび 読み方は
• 支払日 しはらいび 読み方は
• 振込日 ふりこみび Not found on 読み方は, found on a random webpage.

These examples hint that び is the reading of the productive suffix. But is it really so? Are there words that are formed this way, but the 日 there would be read e.g. ひ or にち?

I could not find an entry describing this neither in 大辞林, EDICT, goo辞書 nor weblio. That surprises me, because EDICT has a n-suf flag for such suffixes, 大辞林 either directly marks the word as 接尾 or describes its usage as “名詞の下に付いて…”. 性 can stand as an example.

Is there any dictionary that would list this suffix with its reading?

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Answer 1

In cases where 日 is productively attached as a suffix to an already complete word, what is the canonical reading of this character?

Assuming the "canonical reading" you seek means hiragana, then it's basically び. This answer is based on my experience, instead of a documented set of rules as I couldn't find any.

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Are there words that are formed this way, but the 日 there would be read e.g. ひ or にち?

Yes, the day of blessing - 天赦日 may be read as てんしゃにち, although てんしゃび may work too. I believe this meets your criteria as "日" here is indeed productively attached as a suffix, to an already complete word. From such point of view, 天赦日 is no different from 指定日 you specified as an example.

三が日 ends with にち, but this one doesn't meet your criteria, as it's kind of a "one word".

But think about it... according to your criteria, even 翌日 may be applicable. You asked for "cases, when a connecting article の is dropped and 日 becomes a suffix, but does not form an entirely new word with its own meaning and reading." so 翌日 (よくじつ) might work depending on how one would interpret your requirement. If you accept this, there are many more possible "canonical readings" available.

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Is there any dictionary that would list this suffix with its reading?

I can't think of one that would provide the output you seek out of the box. However, any dictionary should suffice if you could manipulate the data. As you're seeking for information on the trailing character of a word, one method would be to fetch all the words, and then filter the results to those containing a 日 at the end.

This isn't limited to Japanese, but you may attach 日 to just about any word and the result will probably make sense. Some of these made-up words become popular among a local group and become a "standard" word, but not "dictionary-worthy". It's similar to slang.

Here is a comparison with practical examples:

帰社日 I bet many Japanese won't understand this word, let alone a dictionary. However in the engineering industry this is a standard word. It's the day an engineer dispatched to a client's office "returns" to the direct employer's company to touch base. Clever word, isn't it?

誕生日 This is definitely in the dictionary as it has established its position as a "word".

So there are countless combinations of "blah" + 日 out there, and you can create one yourself too. But no matter how popular it gets, it's just a pseudo word until the scholars approve it.