The decade of one's life from age 60 through age 69.(noun)
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Use "sixties" in a sentence
"Jong in her sixties is at once too much and too little like Jong in her thirties."
"A typical joke in Punch in the sixties is a picture of a small, nervous-looking gentleman riding through a slum street and a crowd of street-boys closing in on him with shouts Ere comes a swell!"
"Miss Bertha Bowlong, who was governess to the KAISER in the late "sixties," is shortly about to publish her reminiscences of her now all-too-notorious pupil."