N-UNCOUNT 空话;大话;夸夸其谈 If you say that someone's claims or promises are just hot air, you are criticizing them because they are made mainly to impress people and have no real value or meaning. 空话;大话;夸夸其谈 [informal, disapproval]
His justification for the merger was just hot air.
他提出的合并理由只是空话连篇。
I'd come to the conclusion by then that he was all hot air.