Antonyms for the word "itemization" could include concepts such as generalization, simplicity, or abstraction. Rather than breaking things down into specific items, a more general or abstract approach might be taken. Antonyms could also include neglect or omission, where certain details are intentionally left out or ignored. Another antonym might be synthesis, where items are combined or grouped together rather than being broken down into individual parts. Ultimately, the way we approach categorizing and organizing information can vary greatly and yield a wide range of contrasting terms for the word "itemization.