Antiperiodicity is a relatively uncommon word, and there are not many synonyms that convey the same meaning. Generally, antiperiodicity refers to a lack of regular, cyclical patterns. One possible synonym might be irregularity, which conveys a similar sense of unpredictability or variation. Other potential synonyms for antiperiodicity might include non-repetition, non-conformity, or non-sequentiality. These words all suggest a departure from established patterns or norms, and they could be used in contexts where antiperiodicity might be appropriate. While there may not be many direct synonyms for this word, there are many related concepts that could convey similar ideas.