Definition of "mid-thirties" [mid-thirties]

• The time of life between 30 and 40. (noun)

Gnu Collaboartive International Dictionary of English: licensed under The Code Project Open License (CPOL)

• "And I’m having my hair left silver—to keep the respect of my students," she explained deadpan, then added with a smile, "and because in my mid-thirties, which is the approximate age the treatments are supposed to leave me, my hair had just enough gray in it to look faded, and not enough to be a pretty silver."
• "In the mid-thirties the rate shot up to fifteen and climbed to twenty by the end of the decade. . ."
• "He was the DMO (Diving Medical Officer), a lieutenant (Officer Grade 3 in the Navy), and in his mid-thirties (my age at the time)."