Sentence:  When she turned her back to the mirror, the spandex in the material clung tightly to her <WSD>booty</WSD>. Ugh. She was even calling her derriere a "<WSD>booty</WSD>," because that's what her eight-year-old, cartoon-watching nephew called it. Whatever the name for her overcurvaceous backside, it was the bane of her existence. She simply sat too much. Even the two ballet classes a week she took at work, in the hospital exercise studio, did not help. If anything, they made her "<WSD>booty</WSD>" even "bootier". 
Meaning of the word marked with <WSD> tags:  The buttocks.