信口

to blurt sth out / to open one's mouth without thinking

letter / mail / CL:封[feng1] / to trust / to believe / to profess faith in / truthful / confidence / trust / at will / at random

mouth / classifier for things with mouths (people, domestic animals, cannons, wells etc) / classifier for bites or mouthfuls

to speak without thinking (idiom) / to blurt sth out

variant of 信口開河|信口开河[xin4 kou3 kai1 he2]

to speak off the cuff / to casually opine

to speak without thinking; to blurt sth out

to speak without thinking / to blurt sth out