The antonyms of the word "slices up" refer to actions that involve keeping an item whole or intact. The opposite of slicing up is to preserve or maintain. Other antonyms include combine, unite, join, and merge. When an item is not sliced up, it remains as one whole entity. For example, instead of slicing up an apple, you could keep it whole or combine it with other fruits. Similarly, instead of slicing up a cake, you could keep it intact by serving it whole or by joining its pieces together with frosting. Overall, antonyms of slice up emphasize keeping an item as a single, complete entity.