something unspoken; unspoken matter
Refers to things left unsaid, often with a nuance of something that should have been said or is deliberately not spoken. Used in phrases like 口無しの約束 (unspoken promise).
二人の間には口無しの了解があった。
There was an unspoken understanding between the two of them.
non-functional mouth; mouth that cannot speak
Describes a mouth that is physically unable to speak or is treated as if it cannot speak. Rare standalone use; more often seen in literary or metaphorical contexts.
その人形は口無しの顔で、何も語らなかった。
The doll had a mouthless face and said nothing.
Compound of 口 (mouth) and 無し (without). The exact historical derivation is uncertain, but the word literally means 'mouthless' and has developed figurative meanings related to unspoken things.