1ADJ-GRADED (指说话、写作或举止)自命不凡的,装腔作势的 If someone's way of speaking, writing, or behaving is portentous, they speak, write, or behave more seriously than necessary because they want to impress other people. (指说话、写作或举止)自命不凡的,装腔作势的 [formal, disapproval]
There was nothing portentous or solemn about him. He was bubbling with humour.