pet phrase; favorite saying; catchphrase
A phrase someone says repeatedly or characteristically, often without noticing it. It can be affectionate, neutral, or mildly critical depending on context.
His pet phrase is, “Well, somehow it will work out.”
先生は「まずやってみよう」が口癖だった。
The teacher was always saying, “First, let’s try it.”
speech habit; characteristic way of talking
Can refer more broadly to a habitual verbal tic or manner of speaking, not only to one fixed catchphrase.
彼の口癖は、語尾に「さ」をつけることだ。
His speech habit is adding sa to the ends of sentences.
"It's fine" has become his catchphrase.
My mother always says "go to bed early" like it's her catchphrase.
His verbal tic comes out when he's nervous.