忐忑的英文单词是 "anxiety"。这个词来源于古希腊语，原意是"担忧"或"忧虑"。例句：

I feel a sense of anxiety whenever I have to speak in public.（每当我必须在公共场合发言时，我都会感到一种焦虑感。）

She suffers from anxiety and depression.（她患有焦虑和抑郁症。）

His anxiety over the exam was palpable.（他对考试的担忧是很明显的。）