Sentence:  <WSD>Oology</WSD> is the 'pseudo-science' of egg-collecting. For much of the 19th and early 20th centuries this was a respectable and popular activity, very much part of the ornithological establishment. However, as bird protection gradually gained in popularity, egg-collecting declined, and was finally made illegal under various Bird Protection Acts following the Second World War. 
Meaning of the word marked with <WSD> tags:  The hobby or practice of collecting birds' eggs, especially those of wild birds.