人の陰口をきく＝speak ill of a person?


I came a cross the expression かげぐち【陰口】(backbiting) and found it in my
dictionary as follows

> 人の陰口をきく［たたく］｜[speak ill of a person / run a person down] behind his back /
> backbite

When I tried to look up the meaning of きく the only transitive verbs that seem
possible are 聞く＆ 聴く. However these relate to listening or at best "asking"
which does not seem to be quite same thing.

Should I just accept such expressions as idioms? Even if that is the correct
course it seems odd that the entry for 聞く does not mention this use.




_As per[meta](https://japanese.meta.stackexchange.com/questions/593/comments-
are-not-for-answers), I shamelessly take Sindry's comment and make it an
answer._

My dictionary (gjiten) says 口を利く means "to speak, to utter, to mediate".

The same dictionary says 利く is intransitive, so it is probably an idiom.

[口を利く in another
dictionary](http://kotobank.jp/word/%E5%8F%A3%E3%82%92%E5%88%A9%E3%81%8F).

