Sentence:  “<WSD>Mum</WSD>! <WSD>Mum</WSD>!” he shouted out. The laughter stopped. Two bright, sparkling yellow eyes peeped from the hollow. Atop her head were the fluffy ear tufts that his <WSD>mum</WSD> was so proud of because they were fuller and lovelier than those of most Great Horned Owls. It was indeed his <WSD>mum</WSD>! 
Meaning of the word marked with <WSD> tags:  Mother.