11679
On [chat](http://chat.stackexchange.com/transcript/message/8891660#8891660),
Chocolate helped me find some examples of adjectives produced from verbs using
the
[`しい`](http://dic.yahoo.co.jp/dsearch?enc=UTF-8&p=%E3%81%97%E3%81%84&dtype=0&dname=0ss&stype=1&pagenum=11&index=108112300000)
suffix. In the following examples, it appears to attach directly to the 未然形:

> 勇む → 勇ま ＋ しい  
>  悩む → 悩ま ＋ しい  
>  喜ぶ → 喜ば ＋ しい  
>  妬む → 妬ま ＋ しい  
>  呪う → 呪わ ＋ しい  
>  慕う → 慕わ ＋ しい  
>  好む → 好ま ＋ しい  
>  好む → 好も ＋ しい  
>  頼む → 頼も ＋ しい

But in these last two examples, there seems to be an extra `わ` inserted:

> 嘆く → 嘆か ＋ わ ＋ しい  
>  忌む → 忌ま ＋ わ ＋ しい

I can't seem to find a dictionary entry for `わ` or `わしい`. What is this `わ`?
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2013-04-09T23:02:08.527
11678
2013-04-10T17:31:13.427
question
etymology morphology
What is the わ in 忌まわしい and 嘆かわしい?
The `わ` in these words is actually the 未然形 of the
[継続の助動詞「ふ」](http://kobun.weblio.jp/content/%E3%81%B5), which historically
attached to the 未然形 of other verbs. In this case, the combination of `嘆く` and
`ふ` formed the verb `嘆かふ`, and the combination of `忌む` with `ふ` produced
`忌まふ`. It is these words that combined with the `し` suffix:

> [嘆かふ](http://kobun.weblio.jp/content/%E3%81%AA%E3%81%92%E3%81%8B%E3%81%B5) →
> 嘆かは + し  
>
> [忌まふ](http://dic.yahoo.co.jp/dsearch?p=%E5%BF%8C%E3%81%BE%E3%81%B5&stype=0&dtype=0&dname=0ss)
> → 忌まは + し

In modern Japanese, the `は` becomes `わ`, and the classical 終止形 `し` is replaced
with the 連体形 `しき`, which loses its /k/ and becomes `しい`:

> 嘆かは + し → 嘆かわ + しい  
>  忌まは + し → 忌まわ + しい

So as you can see, these words aren't really exceptions. Your list includes
`呪う` and `呪わしい`, and that word can be explained in the same way. And in all of
these examples, the suffix `しい` is attaching directly the 未然形 of a verb.

By the way, there's some interesting discussion in English of the auxiliary
`ふ` in [this blog post on
tumblr](http://bottlegrotto.tumblr.com/post/1117231887/o-repetition-and-
continuation-auxiliary-verb).
CC BY-SA 3.0
2013-04-09T23:02:08.527
11679
2013-04-10T17:31:13.427
2013-04-10T17:31:13.427
11678
answer