口くちの減へらない

also: くちのへらん

Meanings

expression, noun-modifying (irregular)

always having a comeback; fast-talking; never at a loss for words

Describes someone who always has a quick, often sharp or argumentative reply; frequently used in a derogatory or critical way. The expression is a fixed prenominal phrase modifying a noun (e.g., 口の減らない人).

Kanji

口mouth
減dwindle, decrease, reduce

Related words

口くちが減へらない
The predicative form meaning 'to be talkative' or 'to always have a retort'; 口の減らない is the prenominal form used directly before a noun.
口くちが達たっ者しゃ
Means 'eloquent' or 'glib', often with a positive or neutral nuance, while 口の減らない carries a more negative, argumentative tone.

Written forms

口くちの減へらない
Standard kanji-kana spelling for this fixed expression.
口くちの減へらん
Search-only colloquial contraction; 減らん is a dialectal or casual negative form.
口くちのへらん
Search-only kana spelling of the contracted form.

Etymology

From 口 (mouth) + 減らない (negative of 減る, 'to decrease'), literally 'mouth that does not decrease', implying a never-ending flow of words. The exact origin is uncertain, but it is a common idiomatic expression.