Sentence:  When the staccato, Neptunes-ian single “Boyfriend” was released in March, musical prognosticators were quick to peg the album it portended, Believe, as Justin Bieber's Justified, a grown-and-sexy, R&B-centric departure that evolved <WSD>millennial</WSD> teenybopper Justin Timberlake into one of the unifying pop-music figures of the aughts. 
Meaning of the word marked with <WSD> tags:  Occurring at the end or beginning of a millennium.