動詞 unsay:

1. take back what one has said
   同義詞：swallow, take back, unsay, withdraw

形容詞 unsaid:

1. not made explicit
   同義詞：unexpressed, unstated, unuttered, unverbalized, unverbalised, unvoiced, unspoken

1. Better leave it unsaid.
   不說為妙，說出來反而不好。
2. What is said cannot be unsaid.
   話已出口，無法收回。