I'm wondering what the か in か弱い, か細い and similar words is. It seems to act as an intensifier. The Daijisen tells me simply that this か is a 接頭語, and translates it as いかにも; it doesn't seem to have its own entry or any further explanation. Speculations online seem to include:

  • it is a corruption of 小【こ】, and so is a simple intensifier
  • it implies "obviously 弱い・細い by sight"

My question: what does this prefix mean, and where does it come from? (For bonus points: can anyone give me some more examples, and is this prefix still productive?)

  • 3
    Here is the page that I believe he's referring to with regard to speculation: detail.chiebukuro.yahoo.co.jp/qa/question_detail/q1430062554
    – ssb
    Commented Jul 23, 2013 at 3:59
  • Yes, they were all unjustified and unreferenced, so I didn't bother to include links.
    – Billy
    Commented Jul 23, 2013 at 5:14
  • [The following contains speculation] 全訳古語辞典「か〈接頭〉(主に形容詞又は動詞に付いて)語調を整え又は語意を強める  『か青』『か弱し』『か寄る』」 So it could be used with verbs. 精選版日本国語大辞典 tells us か寄る is used within the Manyoushuu(512), so this prefix is quite old, and its etymology hard to trace. It speculates か with verbs here could be 斯く. Wherever it may come from, could its use with adjectives have developed from this? If so, it must be old indeed, for か黒き occurs in the Manyoushuu(15) as well. My (wild) guess is that being monosyllabic, its origin is mimetic (=sounds emphatic). This sound contains emphasis in the mimetic かっと(なる).
    – blutorange
    Commented Jul 23, 2013 at 6:52

3 Answers 3


The best answer you might get with this is that it's "just a prefix." I cannot find any indications of the origins, but it is included in dictionaries and defined simply as a prefix that strengthens meaning:


I can only find the one page with the theory that it comes from 小 so I don't know how much validity we can give it. It's probably just an old prefix that fell out of use but remains as a relic in a few set words.

I welcome anyone who can prove me wrong, though.

  • I suspect the 小 theory is nonsense too, but it's among the more believable theories I found! か黒い is new to me. Thanks.
    – Billy
    Commented Jul 23, 2013 at 4:50

弱い or 細い sounds straightforward and a little intense to us Japanese.

This prefix "か" soften the meaning and add some "kawaii".

So か弱い or か細い is a euphemistic expression for something "kawaii".


か弱い女の子 weak (and kawaii, or lovable, adorable) girl

か細い声 weak (and kawaii, or lovable, adorable) voice


I can't really tell you where か comes from, but I do think I can give a name to this sort of prefix. They're sometimes called 発語 (はつご or ほつご), and there are other examples of this category besides just か, including い, お, さ, そ, た, and み.

Here's how 明鏡国語辞典 defines 発語{はつご}:


And here's how 精選版 日本国語大辞典 defines it:


We can find other examples besides the ones in these dictionary entries. For example, I found an old example for た in 広辞苑, 「た易し」. Another example I found in 精選日国 is in the entry for 維新, which says "「維」は「これ」の意の発語".

Of course, the more general term 接頭語 is probably more common, and I'm not sure if 発語 can be said to form a coherent category, but I thought I'd write about this term anyway in case it was helpful :-)

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