Cast before is an idiom that means to predict or anticipate something. Its antonyms, therefore, are words that suggest a lack of foresight or prediction. Words like spontaneity, surprise, unpredictability, and chance could be considered antonyms for cast before. These words imply that something unexpected or spontaneous may occur, making it impossible to cast before. Other antonyms for cast before may be words that suggest an absence of thought or preparation, such as unpreparedness, impromptu or improvisation. Overall, the antonyms for cast before are words that suggest unpredictability, surprise or a lack of preparation.