The office had a feverish atmosphere as the deadline approached.

feverish 是形容词，由名词 fever（发烧）加上后缀 -ish（具有...特性的）构成，字面意思是"像发烧一样的"。这里用来形容办公室气氛"紧张忙碌"，就像发烧时那种高度兴奋、坐立不安的状态。