There are no standard antonyms for the word "pre-contrive" as it is a unique word that signifies something that has been planned or devised beforehand. However, one can use various words to indicate the opposite of pre-contrive, such as "spontaneous," "unplanned," "unintended," and "random." These words indicate something that is not pre-planned but occurs naturally, without any prior thought or preparation. For instance, when we say a conversation was spontaneous, we mean it wasn't pre-planned, or when we describe an event as random, we mean that it wasn't pre-contrived. Therefore, there are no direct antonyms for the word pre-contrive, but other words can be used to convey its opposite meanings.