Formal noun used to express disagreement or a differing opinion, often in business or official settings. Commonly appears in phrases like 異存はありません (I have no objection).
その提案に異存はありません。
I have no objection to that proposal.
何か異存があれば、遠慮なくおっしゃってください。
If you have any objections, please don't hesitate to say so.