unsaid

动词 unsay:

1. take back what one has said
   同义词：swallow, take back, unsay, withdraw

形容词 unsaid:

1. not made explicit
   同义词：unexpressed, unstated, unuttered, unverbalized, unverbalised, unvoiced, unspoken

1. Better leave it unsaid.
   不说为妙，说出来反而不好。
2. What is said cannot be unsaid.
   话已出口，无法收回。