The decade of one's life from age 20 through age 29.(noun)
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Use "twenties" in a sentence
"Maybe not teen motherhood but we live in a culture where – for middle class women certainly – even having children in your twenties is regarded as too young."
"I counted out the four hundred dollars in twenties to make sure it was all there."
"I always laugh when an actor in his lower twenties is given the role of the Ph.D. in a film."