pronunciation - Looking Up Whether 御 Is Read お or ご

Is there a good way to look up whether a 御 prefix is お or ご for a word? I know there is the Chinese origin versus Japanese origin thing (mentioned here). But is there a way to look up for a certain word in particular? For example, 御忙しい and 御自分で. The dictionaries etc that I've looked at never seem to have it.

Answer

I don't know of any dictionary or reference book, but since 御 is most often written as お or ご, as appropriate, you could check the Balanced Corpus of Contemporary Written Japanese (BCCWJ, 少納言, http://www.kotonoha.gr.jp/shonagon) as the proper way of "doing Google counting".

For 忙しい and 自分 the numbers are

お忙しい 217 results
ご忙しい 0 results
お自分 8 results, all of which are in fact なお自分, i.e. unrelated to 御自分
ご自分 835 results

I guess you already know, but for the record, this confirms that it should be 御{お}忙しい and 御{ご}自分.

Just to show that this also works with words which don't follow the rule "お for native Japanese words, ご for Sino-Japanese words":

お電話 393 results
ご電話 0 results

お会計 30 results
ご会計 0 results

Another, quick and dirty way would be to check whether your IME already recognizes one or the other as a unit. (My IME knows お忙しい and ご自分, but suggests 語忙しい or 尾自分 and parses the latter ones as ご＋忙しい and お＋自分. Similarly for 電話 and 会計.)