Sentence:  In his first book since the 2008 <WSD>essay</WSD> collection "Natural Acts: A Sidelong View of Science and Nature", David Quammen looks at the natural world from yet another angle: the search for the next human pandemic, what epidemiologists call “the next big one.” 
Meaning of the word marked with <WSD> tags:  A written composition of moderate length, exploring a particular issue or subject.